I guess it really depends on what your financial obligations are, but personally, I put about 1/8 of my paycheck (I get paid twice a month) into savings, and I take out another 1/8 as an "allowance" that is supposed to last me until the next paycheck. The rest is for bills, but I usually do keep a little bit in my checking "just in case."
Also, the amount that goes into my savings is automatically deducted, so I don't even see it. I found that if I try to pay myself manually, I will put it off. Also, I have something similar to a 401K which is also deducted automatically. When I say 1/8 of my paycheck, it's 1/8 after the 401K payment.
Another tip is if you have automatic deductions from your paycheck such as for medical insurance, 401K, or parking, see if it can be done pre-tax. It will add a few dollars to your paycheck. For me, it also keeps me from getting too large of a tax refund (I know this will vary for different people). While I used to think that it's great to get such a large refund, a friend of mine who is a financial planner said, "it's your money to begin with! Your goal should be to try to break as even as possible at tax time, not receive a big refund!"