Photos: Top, Shutterstock; Steps 1–3, James Michelfelder.
1. Hold a dumbbell in each hand with arms at your sides and palms facing forward.
2. Without moving your upper arm, curl the weights up. Make sure you don't lean backward to move the dumbbell—focus strictly on your arms. If you're doing alternating curl and presses, only lift one dumbbell.
3. Press the dumbbells overhead, rotating the dumbbells until your palms are facing away from your body at the top of the press. Take a short pause, then slowly lower the dumbbell back to the starting position, with palms facing your body. That's one rep. If you're doing alternating curl and presses, only raise one dumbbell, then bring it back to starting position before lifting the other dumbbell.