Help with flop aggression

[crownjules]

Greets all. I've logged just over 6000 hands at $.5/1 over the past two months or so. From Nov - Dec, my aggression stats (over 4000 hands) were the following:

Overall Aggression: 2.01
Flop: 1.21
Turn: 2.35
River: 2.87

Over the past week or so, after a hiatus from poker in which I read over the books, my aggression stats (over 2000 hands) are as follows:

Overall Aggression: 2.57
Flop: 1.49
Turn: 3.65
River: 3.31

Obviously, I'm happy that I've managed to push up my aggression level (and as a result, I'm +BB rather then very -BB). But I'm still very dissatisfied with my flop aggression. As I understand it, your aggression should be about equal on all streets.

Are there any general tips that I could benefit from? To provide a few 'for instances', I find that I never know what the correct action is if for say:

1) My PP is somewhere in the middle of the flop (lower or higher then middle pair)
2) My PP is lower then anything on the flop
3) I flop middle/low pair with a backdoor flush and/or straight draw

Thanks all.