This blog post (Mr. Money Mustache) is a good place to start:
The 4% Rule
I have found that blog, which focuses on financial independence and early retirement, to be informative and entertaining.
There is also this handy calculator:
FIREcalc. It uses all possible sequences of historical market returns to show you how long your money could last over the full range of plausible scenarios. Based on my tinkering with it, I prefer a 3% rule if one has a conservative disposition and is planning for a very long retirement.