Poker bankroll management
Nothing is more important for a professional poker player than good bankroll managing. If you are just getting started trying to build a big bankroll, then this is even more important. Whether you play tournaments or cash games, you need a plan - meaning you must know where you want to go and how to get there.
Setting manageable goals
First, take a look at your current situation: how much money do you have at your disposal, and what games are you best at. Then, set yourself a realistic goal, to be reached within the next 3 months, and another one for the 3 months after that. Go to work, and after 3 months have passed, check whether you managed to reach that goal.
In terms of bankroll, a goal would look like: Use your $500 bankroll, play NL cash games $0,50/$1 and try to get to the point where your bankroll is at least $1000. Be sure not to play higher levels unless you have accumulated a bankroll of at least 500 Big Blinds. If you have been consistently winning at that level over a longer period of time, then move on to the next level.
MTT tournament bankroll guidelines
If you are a MTT tournament player, divide your bankroll by 20 - that gives you a maximum buy-in that you can afford to play. If you cannot find tournaments with a low enough buy-in (which, if you are playing online, should not be a problem at all), go for satellites and try to win seats for bigger events. The latter strategy works very well if you want to focus on live tournaments.
Also, you need to keep your expenses low, especially at the beginning. Travelling to play live games can be expensive - flights or gas expenses, plus hotels and eating out can make a serious dent in your bankroll. When you play major MTT events with 500+ players, it is perfectly normal to not make it into the money 20 times in a row - even if you play at your best. Try to start out with tournaments close to home, so that you would not need a hotel. Bring some snacks or sandwiches and save some money.
Bigger bankroll - now what?
Ok, now you have won some money already and your bankroll is big enough, what do you do now? Well, you still stick to a level that you can afford, but bear in mind that the higher you go (in cash games), the stronger the competition will be. I'd suggest that if you want to play $5/10 NL, you should have a $10.000 bankroll. Even with that kind of bankroll, you can go bankrupt. Make sure to adapt your level as soon as you have lost more than 25% of that bankroll and try to rebuild it a a level that you have been beating!
If you have built your bankroll playing tournaments, then you can afford to spend a little more on travel expenses. Now you want to look out for tournaments with softer competition, maybe a little overlay because of high prize money guarantees. Bear in mind that just because you can afford to buy in to the main event right away, that does not mean you should pass on the satellites and get in cheaply. Even top pros with huge bankrolls play satellites to save money, and it is a good practice run for the main event as well.