All the shared tips on familiarity, continuity, and incentives are bound to help frazzled parents out there. Reward systems work well for many toddlers but not so much for others; mine responded well to a bit of healthy competition. We made it into a game where we kept track of his progress on a chart and awarded small prizes for consecutive successful attempts. That said, I wouldn't recommend this if your child is sensitive or doesn't take losses well - it could be stressful for them!
For those who might try the reward system, I've found that prizes don't have to be expensive or extravagant. Simple favors worked for us - my son was (and still is) obsessed with balloons, so that was our go-to incentive for many early milestones!