Butylated hydroxytoluene (BHT), also known as dibutylhydroxytoluene, is a lipophilic organic compound, chemically a derivative of phenol, that is useful for its antioxidant properties. European and U.S. regulations allow small amounts to be used as a food additive.
Like others have said, it depends... If you're doing sets of 8-12 reps with moderate weights, rest 60-90 seconds. if you're doing high weight low rep (3-5 reps), then rest 2 minutes And if you're doing real heavy stuff like squats, deadlifts, I'd recommend at least 3 minutes.
By initial experimentation and for each exercise, choose a weight such that the tenth lift, push, or pull of the first set is somewhat difficult but not too difficult, to complete. Rest the allocated time, usually 30 to 60 seconds between sets.