You should try to approach every scene, like this...

To start with maybe...
Here are some of
Paul's suggestions
1-5

#1) Even If you can't remember things easily, take notes.
If you can remember things,lucky you! Still take notes! Draw pictures? Anything to help you remember the scenes of the crime.
A camera always works best, but you still want to take notes regardless, than do so.

#2)There are many different scenes to deal with, which can vary on how one should investigate them?
Pay very close attention to every detail! Try not to rule anything out.
Or at least try to keep some of it, in the back of your mind.


#3)Every sense you have. Take it all in, and remember it all. The first time and every time at every crime scene.
You don't want to forget the crime scene and how it originally was. The atmosphere,smells and if there are people? Smells are hard to distinguish or explain, so learn to use your nose as much as possible. Simply, take everything in.

#4) There can be Weird Possibilities?
Evidence that has gotten away?
Something, somewhere else, or someone else, somehow has the evidence?
There may be other thing's you've not considered?
Who could have contaminated the scene without anyone or even themselves knowing it?

#5)The way you feel, could be a clue?
Where would you leave a clue?
Put yourself in their position and imagine why, or what they could be thinking about.
Ask "why"? Why would they would do such a thing? For some kind of personal gain?
You don't know unless you investigate.
I call it the "perpetrators view"