I like your Aasimar idea and I would probably go 18 Char, 14 Dex, and 14 Con, but 16 Char, 16 Dex, and 14 Con would be good too. I'd be tempted to start Warlock with a 14 Dex for light armor. This may not be the popular choice, but I really like the Moderately Armored Feat for Warlocks. It lets...