I just kegged for the first time (also first brew) and think that my experiences may be informative.
* two 2.5G cornelius-style kegs
* one faucet
* one CO2 line
I will be doing half batches so I want to be able to smoothly switch from keg to keg to keg, so I thought force carbing would be best - and still do. I also thought that to do this as quickly as possible I would follow the instruction from Charlie's book. This meant turning up to 25 PSI and shaking. I would *really not recommend this.* It's quite likely I misread something, but I discovered it is really easy to overcarbonate 2.5G (or maybe just convince yourself you have) by shaking it. In an attempt to reduce pressure I used my manual blowoff valve and sprayed beer foam all over the place!
After a bit more reading I decided that shaking is okay, but I at least will be only keeping serving pressure while shaking. It's actually pretty neat to do. You shake the keg up pretty good and then pause and you can hear the regulator dump a bunch of CO2 to replace what got absorbed out of the head space. Then you shake again and pause again, etc. Without the increased pressure this can mean a lot of shaking. (I thought I was done and ended up drinking a pint of tasty enough but extremely flat beer.)
The most foolproof way is what has already been mentioned - just hooking up at serving pressure and waiting - but if you want to speed things up a bit I recommend you don't get too greedy like me. It can cause more of a headache than any Belgian Quad.