Following a tight-aggressive strategy, you should be playing very few hands in early position (i.e., the three seats to the left of the big blind). As a beginner, you should limit your play to big pair (TT-AA) and an ace with a another big card, like AK or AQ. And when you play any of these hands, you should start with a raise. Let the field know you have good cards.
When you start playing at low limits, you'll find a lot of people playing junk hands in almost every position -- hands like J-2 suited. This is simply a mistake. You'll also find people attempting to slowplay big starting hands, like KK and AA. This is a very, very bad idea. There are a lot of unschooled players out there, particularly at sites like Party Poker. And these are the people you're going to win money from.
Now on to middle position.
