Yea, stealing blinds can be tricky especially when playing against bad players because you'll steal with rags in the small blind while everyone else has folded and the BB will call you with 72o and now your on the edge of your seat hoping this fool doesn't hit. Happens all the time, so I try to avoid stealing from the SB most of the time because people simply don't like to be pushed around and they take it personally and loosen up. Sometimes you have to though.
I've noticed that the best places to steal from are the CO or just before. Most won't agree with this next part...it does seem ridiculous, but stealing from UTG is something to consider and has worked well for me, but you really have to know your opponents to pull it off and it's a risk (which is exactly why people end up giving you credit for a monster). Also, if you notice any limpers or min raisers at a final table they are more often than not begging you to steal on 'em, so oblige them!
EDIT: I just realized that you should porobably understand that the idea of stealing blinds is as you claim not to have much of a concept on it. Basically the goal is to use your chips as tools to get more chips when it's highly probable that your opponents are weak and would not want to put their tourneys on the line with their respective hand again against your stack. With that said, if you play by the book as you should when you are becoming accustomed to stealing , the best places to steal from are the button and the CO if everyone else has folded around to you because it is pretty unlikely that the remaining players to your left will have anything worth while and fold to you. Stack size is also a factor here. If your the small stack you will want to start stealing blinds before your stack ends up being so small that it's not respected and the big stacks feel compelled to call you if for no other reason than they can. This is why it is important not to play too many hands at a final table and stay tight, so that when you steal on people they give you credit for having the hand and you make it easier or necessary for them to lay it down. STealing from UTG is more advanced and you should ignore that for now until you are comfortable. If you are the big stack and have position to steal on smaller stacks it is important to do so to prevent the smaller stacks from raking in the blinds and living longer in the tourney than they should. They are only going to call you if they are bad players or have a monster. Again it's unlikesly the later is true if you have position ( button, CO or small blind) and everyone else has folded to you.