The challenges that a preschooler and toddler bring to ones life can be somewhat difficult at times. It is important to be creative and think on your toes. One of the "incentives" that has been successful for our family has been a "treasure chest" of stickers. The treasure chest can be an art activity by itself for one day or over a course of several days depending on how decorative you want it to be.
Many craft and hobby stores have various types of decoupage type of items that can be decorated. Our family has favored the treasure chest.
It can be decorated with glitter glue, markers, crayons, stickers, paint, etc. Inside of the treasure chest when we have needed something of an incentive, whether it was "if you do this...you can select a sticker to wear"...or "you can get a new sticker if you do this", and better yet, "go get your treasure chest and you can pick a sticker to put on your chore chart".
The ideas really are endless of even what you would like to put inside of the treasure chest. It could also hold little surprises if a child did well for the week...little surprises if you are trying to potty train, being on good behavior, etc.