Tip: Do This Set-Rep Scheme for Size

When you first start lifting weights, just about any set-rep scheme will work. Three sets of ten reps (3 x 10) seems to be the universal approach. That works... until it doesn't. There are several effective set-rep protocols, but here's a simple one to try if your main goal is gaining muscle.

10/8/6/15-20 using 50-75% of 1RM

Set 1: 60% of 1RM (one rep max) x 10 reps
Set 2: 70% x 8
Set 3: 75% x 6
Set 4: 50% x 15-20 reps

The first three sets are done with gradually heavier weights and progressively fewer reps.
The fourth set will finish you off with high-rep pump work.

This approach is very effective for pure muscle growth since it attacks all the zones that have the greatest impact on hypertrophy.

This method will be even more effective when used with proper workout nutrition (including pre-workout nutrition) because the main benefit of the last high-rep set is to bring nutrient-rich blood into the muscle that was stimulated during the earlier, heavier sets.