I could write pages and pages on BRM and how it should be adjusted depending on your situation and aspirations within the game, but this is just me.
I aim to play tournaments so that my bankroll is more than 100 average buy-ins (ABI). That means that say I have $500 in by BR, I'm not restricted to a max buy-in of $5, but I aim to keep a session of 5 tournaments at a maximum of $25 or a session of 10 tournaments at a maximum of $50. This allows me to a) be more selective in the tournaments that I play (better structures, or softer fields, etc.) and b) take calculated shots at higher buy-in tournaments, without blowing my BR if those shots don't work out. This gives me the best opportunity to grow my BR, while keeping the risk of losing it all as low as possible. I NEVER buy-in to a tournament for more than 5% of my BR.
In terms of when to move up stakes, I would take shots, the moment the next buy-in level is less than 4% of my BR. So if the next buy-in level is $30, I would take a shot as soon as I got to $750, but if that didn't work out, I wouldn't be able to take another shot until I got to $750 again. The reason, I say 4% instead of 5% is that I don't want to be taking shots at an unknown level at the absolute limit of my BRM.
Very occasionally, I might adopt what I call a hybrid approach to BRM where I essentially sell action to myself. Let me explain...
Say I have that same $500 BR. My absolute maximum buy-in would be $25, but there is an online series on and there is a juicy $50 game that is just full of fish that have satellited in from hundreds of $1 satellites. My BRM would say I can't play this game, even though I reckon have have a fairly decent edge over the average of the field. I would seriously consider selling action, but not to a bunch of other people, who are going to profit from my edge, I would sell it to myself from my real world money or my "life roll". I would deposit $25 to the
poker site and split the action 50/50 between my poker bank roll and my life roll. Say I do really well and end up bagging $500, I would then return $250 to my life roll and increase my poker roll by $250. If things don't go to plan, I have only lost $25 from by BR and I will have to play more $1 and $2 games to help average that out and reduce the variance, and I've only lost $25 from my life roll, which is not significant enough to be a problem.
Note; I keep my poker bank roll and life roll as two completely separate things. I keep very strict BRM to ensure that I never have to deposit from my life roll. I sell action to myself a maximum of twice a year, almost as a treat to myself. If you're regularly selling action to yourself, then it can quickly become a dangerous situation where you are essentially bankrolling poker from your life roll and that is not a healthy situation to be in.