Here's what I do (there are a million variations in various threads so not mine persay). Rack your finished brew into a keg. Hook it up to your CO2 and burp it like 15 times (or more, I'm OCD and I don't count) to purge the o2 if you don't do o2 free transfers. Dial the regulator up to 25-30 psi and just leave it, in the fridge on the gas for 36 hours. I typically do all this at night before I go to bed day 1. Then wait 36 hours. Turn off/disconnect the gas, purge the gas from the keg, set the regulator to serving pressure and turn on/reconnect the gas (typically I do this before work on day 3). Leave it for 8-12 hours (or until I get home from work that day). Drink well carbed beer at your leisure. Never had a problem w/ over carbing doing this method.
If you do get slightly over carbed just burp the keg every hour or so, any carb beyond your serving pressure will come out of solution and into the head space (equilibriam and all that), by burping it you'll vent that extra head space pressure and go again until the liquid and gas pressure are the same (aka serving pressure) annoying but not going to hurt anything.