THE TOWEL TRICK
When the vast majority of people do incline dumbbell curls, their head comes off the bench. Half of them do it to gawk at their awesome selves in the mirror, but the other half likely do it because they've given themselves a permanent forward-head posture by texting during walking, eating, and making sweet, sweet love.If you're in that latter half, try sticking a rolled up towel underneath your neck and keep your neck pressed against it and your head flat against the bench. It'll automatically increase your strength.