When you get called for a fire of any kind, theres always a few major aspects to think of. First and foremost is your safety and the safety of your co firefighters. Next is what is burning and how do I put it out. The last I am going to mention is very important also. How did this fire start and how do I make measures to preserve evidence which may be around (and you may not see). Evidence is sometimes hard to detect, we must use our instincts to try to point out the not so obvious. Burn patterns are a huge resource for determining the location of point of orgin. It can tell you whether it was a fast burn or a slow burn. (the smoke cone on the walls.) Fast burns are an indicator that an accelerant may have been used.) Looking at incandescent lightbulbs is another resource which can point to the direction the fire started. A lightbulb will melt towards the direction the fire originates. With this being said, we must do a major amount of training with thermal imaging cameras. With the cameras of today being so advanced, you can limit the destruction of walls, and ceilings. If the camera says theres no fire behind the wall, leave it be. The old days of gutting a house are gone because someone may have felt heat behind the wall. If you are fighting a fire, and you see an incendiary device, note the location, and take EVERY precaution to not touch it. Fingerprints are a classic nail in the coffin in some cases. If you pick it up and take a look at what it is, you technically are part of the chain of custody, and if multiple hands pass it around, the chance of it being thrown out of court as not admissable isn't worth it. There are many steps to collect evidence and preserve the chain of custody which have to be followed, or else your little firebug will walk and strike again.
If you need help with evidence preservation, and or what to look for, contact your fire marshals office and ask them if there are any training classes they can provide to help you spot and avoid the areas which are indicators of point of orgin.
I will include this also just so you can see with a clearer vision as to the importance. In a fire north of where I live a jouvenile female set fire to her bed. Jouvenile fire setters have a few reasons for creating fires. Her reason was simple. She was being assaulted sexually on the bed she burned. It was the quick thinking of the firefighters inside to preserve the scene, and it leaded to the arrest of the stepfather for molestation and sexual assault. Now if these firefighters had not preserved the scene, the marshal wouldn't have had that angle to look at.
As I stated before I am an Assistant Deputy State Fire Marshal and also certified in basic evidence collection. ALWAYS have an eye out to save shred of evidence no matter the size, shape, or weight, it could be the one mitigating factor to put your pyro behind bars. It could also have far reaching affects beyond the fire starter