Stock rebuild or higher performance cam?
Hydraulic or solid lifters?
Solid lifters on a standard cam are easy, just tighten them down until you have resistance on your feeler gauge, about 7intake, 9exhaust would be my guess, you'd have to reference a manual.
If you have a new cam look at the cam card and see what it asks for, it will usually give a hot and cold setting. Start with the cold setting and then check after it has run and gotten hot.
Some people like to clearance with the motor running. I've found no problems with shutting it off, immediately removing the valve cover (remove the bolts while it is running, and then setting them with it off. You can use a cut up valve cover to keep it from making too big a mess if you do them running.
Hydraulic you'll have to reference the manual, it is usually something like 1/4 or 1/2 turn past zero clearance I think.
Hope this helps.