> Pay yourself a monthly amount and don't touch the rest.

This is exactly what I do. I used to not and it sucked. I would never ever go back.

I would also add the micro-tip that I set up not only separate accounts for business and personal, but separate accounts within person for "money I can blow" and "money to live on". My wife and I each have our own money-to-blow account which totally prevents arguments about wasteful purchases.