Break the task into parts. For example, making a bed means smoothing sheets, fluffing the pillow, and smoothing the top cover.
Explain how well the task needs to be done to meet your expectations. How smooth? How straight? By when does it have to be done?
Allow the task to be learned in stages. Start by having your child do just one part of the task. When he can do that well most of the time, add another part until he or she is able to do the whole task.
Compliment when your child does the task or part of the task well. Let him know he or she is doing well. Give details about what was done well.