Keep your classroom organized, and make sure there is a "home" for everything. Provide a shelving system with bins clearly marked with pictures of what each bin should contain.
Be consistent and follow through. Keep your routine structured and organized. When playtime is over, do not move on to the next activity until the cleanup process is complete.
Make the transition easier for the children by telling them that clean-up time is approaching. Small children often need time to adjust before starting a new activity.
Play music while your children participate in clean-up time. Provide music with a tempo that will get them moving and redirect stragglers to a mess that you want them to help with. Turn the music off to let your little helpers know the task is complete.
Offer plenty of praise. Let them know they are doing a good job. A simple sticker as a reward is a good motivator -- encourage each child to collect a sticker every day.