Since this thread is active again...may I suggest that one of the best ways to learn technique is to shoot EVERYTHING for a while, then learn by experience as you sort and post-process your inventory. Eventually, you'll discover that three basic rules are almost inviolable:
1) A true photographer thinks in terms of light more than any other factor;
2) The Rule of Thirds
really does determine whether a photo is interesting; and
3) The camera you have is always better than the one you don't.
For example, I recently used my Nexus 5X phone to shoot this image of firefighters mopping up a bigrig cab that burned to the ground along I-70:
Regarding (3), the 5X wasn't ideal (I wasn't even able to get a good flame shot while the rig was still burning), but it was what I had when we came upon the fire. For (1), note the high-contrast and the coloration provided by the numerous emergency vehicle flashers; I wasn't thinking
"is the light right?" when I took the picture, it just happened based on experience. As for (2), I wasn't actively thinking about that, either, yet look at where the subjects lined up: