Here are a few things I have picked up along the way in my first year of playing online poker and in home games.  You should try to only play about 20- 30 % of the hands at any given table.  Most poker rooms have a table that shows you hands played and pots won.  I know Full Tilt has it broken down in several categories including hands played, flops seen, rivers seen and then rivers seen along with the percentages of the pots won on each level. 

Now here are some of the common mistakes players tend to make, myself included.  The first mistake I made was holding on to a decent hand when I know I’m beat but can’t lay it down.  The next is taking a call on a beat with something like bottom pair or just a gut shot straight draw.  I also don’t recommend playing a lot of hands.  Don’t get me wrong if I’m playing the $0.5 – $0.10 tables I’d throw all this out and play everything, but once you get to higher stakes you should play only a small percentage of the hands.  The next mistake I used to make is trying to slow play big hands.  I learned that if you slow play you are asking to get out flopped with crappy cards.