Having a "proper" bankroll assumes that you will be sticking to a specific buy-in level. But if you're willing to move down, you can get away with less. Just be sure you have a plan and stick to it
My table strategy:
If I were you, assuming you're on PokerStars
and playing one table at a time, I'd start at the $.01/$.02 tables.
When you earn $20 move up to the $.02/$.05 tables as a reward.
Should you use up that $20 at the $.02/$.05 level, move back down to the $.01/$.02 tables.
Once you make $30 there ($250 BR) move up to $.05/$.10. Should you lose that $30, move back down. Lose an additional $20 ($200 BR) and move back down to the $.01/$.02 tables again.
Earn $50 there (bankroll at $300), try playing the $10 tables. If you lose your $50 move down.
Make $150 at the $10 tables ($450 bankroll) and try moving up to the $25 tables. However, this time if you get under $400 I'd move down.
I'm playing the $25 ring games now, and won't move up until I hit $1,000.
Of course you play tournaments as well, which makes things more complicated.
First off, use PokerTracker to keep track of your ring and tournament winnings.
Second, I'd move up and down on tables based on how much I won at the previous level regardless of how much my bankroll has increased
because of tournaments. However, if your bankroll has decreased
because of tournaments, do not move up until your total bankroll is at the appropriate level.
And of course, moving up and down tournaments should be based on your bankroll.
Another option might be dedicating only half of your winnings to the next level of play
. That is, if you make $100 in the $1 S&G's, use up to $50 of that in the $2 S&G's. If you make $200 there, use up to $100 of that at the $3 S$G's. Etc. Then when you move back down a level, you're still ahead of where you were when you were playing it before.