We cannot stress this enough. While you always want to pay attention to how people are playing, online poker players are always coming and going, which doesn't give you time to feel them out. Taking notes can help you keep a record should you play against these opponents again. The main characteristics to note about a player are: smart or not; aggressive or passive; tight or loose; straight up or bluffs; bets out a draw or not, and what kinds of hands the player plays or the pre-flops are being raised with. Yes, this is a lot of information to note, but it will help you in the long run.
More often than not, only the winning hand is shown on the river. However, it’s interesting to note what the loser was holding. Simply click on the hand number at the top right of the screen to switch to the Hand History screen where losing called hands can be seen. We recommend doing this in conjunction with player notes to get a good idea of what a player is willing to play with on the river. Showdown information is always the most critical, as you can analyze their decision making process from the ground up.

This is really just a general poker tip, but it still catches even the poker pros at times. At MGMPalace, if you find that you are being outplayed, outclassed or even if you are just unlucky at the table, it's okay to leave.
Don't think about getting your money back or getting revenge on the player that rivered you for the 3rd time. If you are losing money at your table, you do NOT have a good table image - no matter what you might think. Not only are you not in a good mood, which puts you on tilt (admit it or not), but other players will be more likely to make plays against you. This makes your game harder in more ways than you could possibly be comfortable with.
If the game gets short-handed (6 players or less) and you are not familiar with short-handed play, then you may want to leave the game. Playing short-handed is an easy way to lose a lot of money if you don't know what you are doing. This happens all the time when a table breaks up and there are two solid players and three other guys who don't realize they are about to get run over. Don't be a road kill when all it takes is a single click.
If you've been doing your homework, you'll know that you should always sit in with a minimum of 20 times the Big Blind at any poker table. In online poker, this should be more along the lines of at least 40 times the Big Blind. You should think about starting with 100 times the Big Blind. Why? First, don't ever be in the position of holding the nuts and not having enough money to raise the pot. It happens too often that a player will have flopped a full house in a $3/$6 game, but has only $12 remaining in his bankroll. The player could have made a killing if it weren't for the fact that he/she was playing with a small stack. Protect your computer.
It never hurts to take extra precautions when it comes to protecting your computer and poker information. Anti-virus software is good, but the real threats are Spyware and Trojans. We recommend getting the Ad-Aware software which is a very popular (and free!) anti-spyware software that thoroughly cleans your system of tracking junk. Firewall software is great, too, and highly recommended. Admittedly, the odds of someone coming after you for your poker passwords are slim, but why risk it?
If you play poker long enough, you're going to make mistakes. Everyone with enough experience has probably misread their cards at some point or another (usually after a long stretch), especially flushes. Using a four-colored deck makes it much easier to identify flushes (and more importantly flush draw threats) and enables you to focus your attention elsewhere.