The secret to drifting for catfish is to first find a good location were the top of the lake or river will hold catfish's will have in a river a good flow of well oxygen and structure and it wont hurt to find the bait.
That brings us to bait, your bait should match the hatch if you see a lot of shad bingo use shad,or if you notice a lot of craw-fish POW use craw fish.
But how to prepare your bait well that's were it gets tricky some days,those cats like cut bait or maybe just the sides,it could be they like live bait. Well all that depends on the fish that day so try a little of all trial and error makes the best fisherman.
Your rig the best rigs for Drifting is a 3 way swivel,with your bait raised off the bottom. This works best because catfish have a hard time pick-in things up right on the bottom, Yea I know that doesnt sound like what your buddy told ya but its true. Look at a catfish its bottom lip its longer than its top speacialie on a Flathead (yellow cat) this is why I keep my bait up off the bottom. You can also drift with a water balloon this work great it keeps your bait at a chosen depth and works like a bobber.
You can add water to the balloon to make it drift slower or make the balloon bigger to drift faster. Just tie the balloon on at the depth you would like to fish and let her go,Its almost like jug fishing but you can fight that big old nasty fish all the way to the boat.
Sinkers just use the minimum amount to keep your bait down don't try to use a truck axle or the kitchen sink start with 3/8 and go up from there.
This will give your bait a good natural drift that will not get hung up as much as a heavy wieght will. The line hooked to your sinker should also be light (if I have 20lb line on my bait line I will use 8lb on the sinker) this will help when you get hung up the sinker will break off an all you will have to do is tie on a new sinker.
All of this is just a start to a long and fun time of drifting. Drifting for cats can be one of the most successful ways to catch big fish and lots of fish.
A good location is bellow damns, wind blown lakes, and wide open rivers.
If you practice and keep fresh bait you will soon find that you are a expert at the art of drift fishing.
Good luck and tell me how you do!!!!!!!!