A tool I like to use to pick names is the U.S. Social Security Administration's website: Popular Baby Names. I think using popular names helps readers identify with characters. The site is great, moreover, because you can input the year of birth and get the top names for that year. For example, in 1910, the top names were John and Mary. In 1960, the top names were David and Mary. And in 2010, the top names were Jacob and Isabella. Hhm... I'm starting to see why I have some character names repeated. :)
How do you pick your character names? How do you avoid repeating names?