Kitchens tend to have a large amount of oil and grease that gets deposited on the walls. It is very important to remove this oily residue in order to have good paint adhesion. It would be best to wash the walls with TSP and prime the surface with something like Kilz before applying a new coat of paint.
I would make sure that you are painting it the color you want and it is going to match really well. Look at all the colors you have currently and make a choice than.
Appliance, flooring, countertop, and cabinet colors should always be considered when choosing paint for the kitchen. Ensure all defects in the walls are repaired and use a semi-gloss finish.