Do's:

1: Do make sure of client confidentiality desires. Make sure before you do anything else that you know, and preferably have it in writing, what the client wants in terms of confidentiality. Full Confidentiality (i.e. no sharing of findings with anybody but the client), Anonymity (you can share the findings, just nothing that would lead back to the client), or Full Disclosure. You will note that this is the only one numbered, because it is important you do this first as it will effect everything else you do, from basic research to your findings.

Do plenty of research. Always make sure that you don't just take the client's word of what happened, actually look into the history of the property. A lot of 'hauntings' end up being nothing remotely close to what the client thought because the client's base information was faulty.

Do a pre-investigation interview. Make sure that the property owner knows what is involved in your investigation, and that you know what the full situation is.

Do record your interviews. Audio, or preferably video, recordings can be revealing when reviewed later.

Do tag your audio. If you hear something, but know or find what it is, then say what it is. If you don't tag your audio, then not only will you not know what you have, but nobody else will, either. The lack of tagging will call into question anything that you may legitimately find.

Do know where the rest of the team is. Something they may be doing might be the cause of what you are hearing, seeing, or feeling.

Do a full lights-on walk-through tour of the property with the property owner before you even start unloading gear. This will not only give you ideas of where to concentrate your efforts, but will also help to point out potential safety hazards. Take pictures of the house during the interview, and take baseline emf and temperature readings, to use as a reference during analysis.

Do bring a properly sized group. Too many people will cause cross-contamination of evidence, while too few will mean you will probably miss something. If you have to err, err on the side of too few, as you will have the chance to catch something with lower risk of contamination.

Do be fully aware of your equipment, it's capabilities, and it's effects on its surroundings. Equipment can sometimes have unexpected effects ranging from emf spikes and fluctuations to turning remote controlled electronics on and off.

Do always have full permission before entering a property. Make sure the client understands what you will be doing.

Do always make sure that your equipment is ready to go, fresh and replacement batteries as needed, cleaned, and other-wise ready to use in a moment. If a piece of equipment needs modification, do so before you go to the client's. This includes removing camera straps, cords that might get in the way, and tying back long hair.

Do play nice with other groups. It is not a competition. So long as the group is a legitimate group, then sharing information (with the exception of anything held by confidentiality agreements) will only help both groups.

Do make sure you have proper safety equipment. This includes a first aid kit, 2-ways, and possibly even an alternate light source (candles, kerosene lamps, etc.). At the same time, at least one person from the group should be trained in CPR.

Do hold your breath while taking pictures. There are a number of reasons for this. First and foremost, this will remove any accidental breath contamination, especially in cold weather. The other major reason is that holding your breath will actually help to stabilize your picture.

Do map the location and mark the placements of your equipment.

Do be aware of your environment. Most false positives are things that are easily explained once you know the details about when, where, and and the weather of the evidence. Light source placement and reflective surfaces are other major causes of false positives.

Do keep track of environmental conditions of the investigation. This includes not only ambient temperature, but humidity, dew point, barometric pressure, and precipitation. These things are important to people and groups trying to discern a replicable pattern.

Do look for the obvious. Most 'paranormal' events can be explained or debunked.

Do stay in groups of 2 or more. Wandering off solo not only can introduce safety hazards, but it can call into question any evidence you may find. With nobody there with you, there is nobody back your evidence as real.

Do be mentally prepared for the investigation. Being tired, in a bad mood, or feeling ill will not only reduce your ability to notice things around you, but can leave you open for attack should there actually be something there.

Do bring plenty of notepads and pens. Keep track of what you hear, see, and feel. Note what room and what time you experience anything. This is also useful for anybody who believes in or uses automatic writing, as they can sit down at any point and auto-write.

Do write down your experiences and observations before telling anybody else. This will help prevent subconscious altering of memories.

Do have a plan before you show up for the investigation. The property tour will fill in the specific details, but you will need to have at least a general idea of what you are going to do before the tour.

Do make sure the proper authorities know what is planned. Just because the property owners have given you permission to be there does not mean a concerned neighbor might not notice your flashlights and call the authorities.

Do have proper legal identification on you at all times. Ladies, take your driver's license out of your purse and put it in your pocket. You too, guys. This will help in the case of crossed wires and the police stop by.

Do always be straight forward with the police, should they arrive. Sometimes, even though you have permission to be there, the police still stop you to see what you are doing. It happens. Things will resolve themselves faster, and more to your benefit, if you just be honest with the police. It will help for you to also have the contact information for the client so the police on scene can double check your claims.

Do bring food and water. People will get hungry during the investigation, and growling stomachs can be picked up by most recorders. Plus it will prevent your team from raiding the client's fridge.

Do make sure that somebody knows where you are going and how long you will be gone. This is in case something happens and you are unable to call for help.

Do take steps to protect yourself and your team, not only from the paranormal, but from the criminal as well. Even investigators are susceptible to muggings and robbery. Remember, there is no reason to fear the dead, it is the living you need to worry about.

Do follow your instincts. If your gut is telling you to get out, get out. From a purely psychological stand point, if you are being distracted by a desire to leave, then you will miss something that could be evidence.

Do have everybody in the group go over evidence. People hear and see at different ranges. Somebody may catch something you miss, and vice versa. When allowed by the property owner, share your data with other groups. More eyes never hurts, they may be able to explain something that you cannot.

Do watch your language. Try to refrain from using profanities on investigations. Some of us will find that harder than others (I curse like a sailor), but others might find it offensive, whether it is the property owner or the entity claimed to be haunting the place.

Do get plenty of rest before the investigation. As I noted above, being tired will cause you to miss things.

Do always clean up after yourselves. If you leave a mess, then you won't be asked back. In addition, your client will give you a negative word-of-mouth. Word-of-mouth is very important as a way of gaining new clients. For every bad investigation you do, you scare away 10 potential future clients.

Do leave a contact number. If something happens in the future, the client will need somebody to turn to. And, unless you have done something to alienate the client, that will likely be you.

Do remain in contact with the client after the review is over.

Don'ts:

DO NOT PROVOKE! No matter what you see on tv, provoking is not a good idea in a residential. Provoking is designed to anger or annoy whatever is there into revealing itself. That is fine for us, but what about the people who then have to return to their home with a now angry whatever in their homes?

Don't run away. If you need to get out, excuse yourself and walk out calmly and quietly. Get into your car, if you need to. Just do not freak out around the client.

Don't assume anything. If you hear a noise, unless you know what it came from, check it out. Be a proper skeptic, not a pseudo-skeptic. A true skeptic puts aside their own beliefs and opinions, whatever they may be, and looks at something fully open to whatever answer is right.

Don't drink alcohol, smoke, or take any illegal substances before, during, or after an investigation. Not only will it leave a bad impression on the client, but it can (and usually does) contaminate any evidence you find. In the case of alcohol and illegal substances, it reduces your credibility to nothing, even if your evidence, itself, is not tainted.

Don't take pictures while moving. No matter how much 'shake stabilization' a camera claims to have, you will get blurry or distorted images. This is especially true for an analog camera (35mm), which have no stabilization built in.

Don't wear perfume or cologne on an investigation. You would be amazed how far these scents can travel to create 'phantom smells'.

Don't wear light colors. I'm not saying you have to wear black, even though that seems to be what most groups expect you to do, but do wear something darker, like blue or red. Lighter colors, like white and yellow, reflect light more than most people realize. In the dark, even the slightest bit of light on light clothes can seem ethereal from across a room.

Don't be disrespectful. This goes along with provoking. All it will do is make it worse for the people who have to live with the effects of what you do. Ghosts used to be people, too.

Don't play around in front of the client. Yes, you are meant to have fun while doing this, but keep the horseplay away from the client, and to a minimum during the investigation.

Don't fail to show up. If you promise to be there, then be there. If something prevents that from happening, then make sure the property owner knows as soon as possible. Likewise, if you are an investigator in a group being run by somebody else, let your group leader know if you cannot make it.

Don't take just one picture. Always take pictures in groups of three. This way, if you capture something on one picture, you have a better chance to verify what it is.

Don't whisper. If there is audio recording nearby, whispers can sound like evp. Always speak clearly and in a normal tone of voice.

Don't be afraid to refer. If something is outside of your comfort zone or too unfamiliar to you, there is no shame in calling more experienced people for help. There are a lot of well established and knowledgeable people in the field, and they didn't get there by refusing to admit they need help.