If you're newcomer to online poker play then you should be sure to play at the correct level for both your original investment and your ability as a new player. No matter which form of poker you're going to choose, a standard rule of thumb is never to play with more than 10% of your bankroll on a cash table, or to spend more than 5-10% of your account buying into a single table or multi-table tournament.
It can be very tempting to deposit $50 into your account and go straight to the $1-$2 No-Limit tables with your entire investment, but if you do that you're inviting trouble and heartache. A couple of close-run defeats on a $1-$2 No Limit table will very quickly make short work of $50 and you could find yourself going broke more quickly than you might expect. The same can be said of using most or all of your bankroll in one tournament.
By staking no more than 10% of your bankroll on any one game you can avoid being wiped out by a run of bad luck and live to fight another day. No matter how good you are, or think you are, bad luck comes to us all over time and you should never risk your entire account in one go. Play at the levels that suit the safety of your bankroll.
As the size of your account increases then you can move up to higher and higher levels, safe in the knowledge that you are protecting your investment and working your way up the poker ladder.