Okay, so I went from pretty much thinking I knew what I was doing at poker, to being more lost than Alexmr at a whorehouse... I have a lot of situations like this happen, and I'm not sure when exactly I'm sposed to be firing again on the turn and when checking behind to either keep the pot smaller or catch someone bruffin..

$0.25/$0.5 No Limit Holdem
6 players
Converted at

Stacks:
UTG ($15.00)
Hero ($78.25)
CO ($36.80)
BTN ($55.95)
SB ($49.45)
BB ($33.80)

Pre-flop: ($0.75, 6 players) Hero is UTG+1 [Jd]
UTG calls $0.5, Hero raises to $2.25, CO calls $2.25, 2 folds, BB calls $1.75, UTG folds

Flop: [Jh][3s] ($7.5, 3 players)
BB checks, Hero bets $6, 1 fold, BB calls $6

Turn: ($19.5, 2 players)
BB checks, Hero checks

River: ($19.5, 2 players)
BB goes all-in $25.55, Hero calls $25.55

Final Pot: $70.60
BB shows: [Qs]
Hero shows: [Jd]

Hero wins $67.6 ( won +$33.8 )
CO lost -$2.25
BB lost -$33.80
UTG lost -$0.50

So basically... Would it be better to do stuff like this when the guys a 60/40 guy, which he was, or a 60/2 guy or a 30/25 guy or what... Also, would it change anything if you had KK there instead of AJ??? Or should I just be firing away and praying he doesn't have a set???

I would bet the turn. Almost nobody at these stakes check raise bluffs and nobody check raises QJ on this board either, so just bet / fold the turn.