How do you manage your bankroll for NLHE cash games and MTT tournaments, why and what bankroll management (How many buy-ins) do you recommend me?.

 I wanna start playing poker seriously. I have a little more than 400 bucks in my account and I'd like to start in the .08/.16 games (25 buy-ins). Do you think is enough or should I drop down to .05/.10.?

 When (How many buy-ins) would you move up to the next limit?.

Thanks