Actually just looking at picture is going to teach you more than you think. I can't really tell you in solid words what a yellow belly looks like, but I can ID most of them in half a second. Problem with pointers is the variation in the morphs. Like your example fires, they normally have a head stamp but not all of them do. Some take longer than other to grow into their color. Some are orange as babies. some are tan. but for some reason, I can still pick out fires quickly just from all the pictures I have looked at and examples in real life I have seen.
closest thing I can think of to what you are asking is http://ball-pythons.net/forums/forum...-Python-Morphs
Just browse the forums for a couple weeks, you will be surprised what you pick up without even knowing it. then if there is any specific morph that you have questions about, ask. There is no doubt some are harder to pick out than others.