We had similar issues when we first wanted to go digital. We settled them by getting a camera that actually burns the photos onto a CD, which also means you can take about 150 high-quality images before you have to use another .10 cent disc.
While I have had not formal training, more is better, and I always take at least two photos of everything, in case one missed something. Your first photo should be of the case number so that if your disk gets separated from the case jacket, everyone can figure out where it belongs. Dry erase marker on the trunk of the car works well for that, and wipes right off. Start a ways out and get a full photo of the victim/object, get closer and take lots of photos of the injuries/damage from varying distances. Take the photos in sequence; far, closer, near, extreme close up so that you can figure out what exactly you were photographing. Work in photos of DLs and license plates as well as identifyinf face shots so tha you can clearly ID who/what you were photographing. Make sure that what you are photgraphing isn't back lit, and don't be afraid to light things up with a flashlight or provide some indirect lighting by bouncing the beam off nearby objects. I also include rulers or other objects for a frame of reference. When all else fails, go to your wallet; dollar bill is six inches long, and a quarter is an inch in diameter, and can be included in the shot for reference.
That is all I can think of from my limited practical experience.