One of the most common mistakes beginners make is poor bankroll management. I follow the rule of 50 buy-ins for cash games and 100 buy-ins for tournaments. What method do you use?
There are many factors that have influence on BRM.
So the stakes that you play is for cash games an enormous factor,
as is your win rate (BB/100
hands) on those games.
You need a decent sample size of about 50k -100K hands to have good statistical proof of your win rate.
For NL 2 to 5 50 Buy ins may be OK, but if you climb the stakes you have to adjust this rule up.
For tournaments, 100 buy ins is way too small.
Fields are way too big in micro and low stakes MT Tournaments.
It can work, but there is a big chance to lose it all.
A good way to calculate the bankroll requirements is to google for "primedope".
Sorry, but links are not allowed. So google is your friend.
There are good calculators for cash game and tournament variance situations.
Very important is the risk of ruin section, for both cash games and tournaments.
These results give a comprehensive overview of your bankroll needs,
for statistical not going broke.