First off Congratulations are your first place win! Make sure you post that in the March Winnings board if you havent already done so. Coming in first place is always awesome!!
You say you won 150$. First thing I always do is pay myself first when I win something. I would cashout 100$ of that and treat myself and kids to something fun, say a ball game or going sking...even a dinner at OutBack Steak is always nice for us.
It's important to treat yourself to something, reward yourself first! Other wise I hate to say this, but you could put it all in your BR and run the risk of losing alot of it. So do the other..reward yourself!
Take the balance 50$ and rebuild your BR. Shouldnt take you too long to get it back up depending on how many games you play.
Good Luck to you!
Cali
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You can cash with skill
You can go deep with skill
You can't win without luck
I Fear No Stack
"Can't win on skill alone, everyone catches a lucky card"
CalifNaughti - PokerStars
What is the best 
Seriously there are many ways to increase that money. I'm guessing you won the cash in a freeroll and now want to play cash games. Are you a good ring game player or a better tournament player? Personally I am not as comfortable at the cash games and prefer sit n go's and tournaments. I would suggest $5 and under multi table tournaments ( stars has them all day long) . Or you could try 1 table sit n go's for $5 and under buy-ins . As you continue to build your roll , you can slowly move up to higher buy-in events. Good luck to you 
Tetris
