The number one thing besides breakin lube and the right oil is rpm. Upon initial start up, directly to 2500 rpm for 20-30 minutes for cam and lifter break in. Of course you need to have quality parts in your valve train.
Yeah do all the right things like proper break in oil, cam lube, get it started right away (make sure everything is right with fuel, cooling and ignition and you have a timing gun ready to go), hold above 2000 rpm for 20 minutes and that is all you can do. Of course light springs for break in will help if you have heavy springs in it.