A lot of people say that you need to have atleast 100 buyins in your bankroll of the tourment you want to play. This way your bankroll will never go to zero and you can see if you can make some profit without losing your total bankroll with one bad beat.
It is a nice way but personaly I like to play 1.50 dollar sit and goes, but 150 is to much for me to deposit. That is why I just deposited 20 dollars and started playing with that. Sometimes those bad beats can be really anoying and I went to zero multible times but that means that I am not ready to make some real money
with poker. I can win, that is not the problem. I am just not ready to make the profit.
I would recommend to try playing with a relative small bankroll and gain some experience after that you can deposit some more or you made yourself that big bankroll already.
Do not play cashgames in the beginning. Some people will bluff you out everytime and you can't call because your bankroll is not that big.
Sit and goes are the best for starters. Or tourments (not the ones with rebuys) ofcourse.
See you at the tables