I don't play online these days but I play a regular $80 buy in. When I first started this (having previous to this only played small online games), I got outplayed post-flop a few too many times and tightened up pre-flop, coming into the hand with a solid hand makes it much easier to know where you're at.
AT as opposed to T9s for example, you hit that T and you know he's got to have a higher pair or better to beat you and if he does it'll usually be fairly obvious, with the 9 kicker on the other hand, you've really got to know your opponent.
The stronger your hand selection is, the easier it'll be post-flop.
Start off that way and just be observent, it wont take long before experiance kicks in and you can rely on a good read to pull you through.