1. Choose the heaviest dumbbells you think you can curl, and perform as you did the conventional dumbbell curl, but use momentum from your hips to power through the sticking point (halfway up, when the weights are most difficult to lift).
2. Do not lean back as you lift, but get into a rhythm where you rock your torso forward and then extend your hips to complete each rep.
3. Stop each set one rep shy of total failure.