1. Start the curl with the correct body position. A straight body with the shoulders back and down increases loading on the biceps.
  2. Tense the triceps, abs, and glutes before starting a curl.
  3. Contract the biceps as hard as possible while lifting. When the arm is fully flexed, finish the curl by rotating the shoulders up, bringing the elbow higher.
  4. Do not use your front delts and traps to lower the weight. Make the biceps do the work.

Related:  You Don't Know How to Curl

Related:  The Slow Hammer Curl for Bigger Biceps