This is for myself and hopefully others will contribute. After playing for six months (lol), I have found the following things to be true when it comes to the way I approach poker right now:

Play position.
Play the player, not the cards. If you have a read you can outplay.
Poker is about time invested and smart play, not gambling.
Being aggressive post flop wins a lot of pots without showdowns.
It's more about what he doesn't have than what you do have.
There is no shame in folding, river or otherwise. It's a marathon, not a race.
If you're playing low limits and have KK or QQ and an A comes up, he's got the ace.

Anyone else learned anything really important they want to share?