You will need to start by removing the cabinets and cleaning them thoroughly, ensure all grease marks are removed. If any grease or dirt is not cleaned off these spots can make it hard for the paint to adhere to the surface. When you have finished cleaning the cabinets and dried them off you can then sand down any imperfections and where necessary fill them up. When you have finished this you can then apply the primer and allow it time to dry before you can begin painting. When you have finished painting and are happy with the results allow time for the cabinets to dry before reassembling and reinstalling them.