When I am working with new students there are few things that every one of them has in common. Things that I can correct right away. The most important hole in their game is also the most common - a lack of understanding of the importance of position. Position, position, position. Acting last is absolutely the most powerful edge you can have in Hold'em.
Sure you have read enough to have heard this before, so why aren't you following the advice of the best players on earth? Why do you let yourself get into big hands and big pots when you are out of position? Either you hate money and are trying to lose that inheritance as quickly as possible, or you just haven't thought about position in the right way. I'm going to assume it's the latter, but if you do in fact hate money I highly recommend playing Keno professionally, I hear it's a great career.
In order to understand the importance of position, let's look at a hand from two different perspectives and see how much more money you make when you are in position.
You're dealt KK in the big blind, and an aggressive and wild player raises from the button. Whether you smooth call to trap him or reraise to build a bigger pot is not important. The hand will play out the same either way. The flop is J-9-3 rainbow. Now what do you do? If you bet out he may fold, and if you check raise he will certainly fold the majority of his hands. The board is fairly safe, but check/calling and then checking the turn is just really asking to get sucked out on, because he may well check behind you once you call his bet on the flop.
If you check raise the turn your opponent is out of there right away. Even wild players these days know how to fold a hand to a big check raise on the turn. A check raise on the flop leaves you with a tough decision to make on the turn if he calls the flop bet, and you are only going to play a big pot if he has a big hand, because you have tipped your hand badly.
Now let's look at that hand from the other side, where you are in position.
Now the middle position player raises and you must reraise to make sure this isn't going to be a big multi-way pot with the blinds involved. He calls the raise of course, and the flop is the same J-9-3 rainbow that it was before. He checks to you and you bet 2/3rds of the pot, which looks like a standard continuation bet to an aggressive player like him. He will often raise here. My advice? Smooth call and trap.
When your opponent bets the turn, thinking that you only called his bet on the flop with over cards and that you will fold to a good-sized bet on the turn, you can surprise him with an all-in raise because the pot is large by now. You could also just smooth call if the board is very safe. If the turn was another trey this would be a good time for a smooth call. Notice that at anytime in the hand you could raise or slow play, depending on what you felt would be the most effective.
When you have position, you can control the size of the pot on any round. It gives you the opportunity to define your hand early, keep the pot small and just see a showdown, or build a monster pot with well sized raises. Acting last also allows you the opportunity to check behind when you have a draw that isn't worth betting and get a free card.