I just plug it in when I go to bed, unplug it when I wake up in the morning. I can't be on 100% watch to make sure I unplug it the second it charges.
I do, however, use a different charger than what my phone came with. My phone came with a 1.3 mAh charger. I use a 0.7 charger. It charges slower which is theoretically better for the battery. Should take longer to run it down, and also extend the life of the battery.