My kitchen cabinets were covered in shellac years ago. There are dark areas around the knobs and scratch marks on them.
TSP follow directions..it is safe for all surfaces, then do Murphy's oil soap
Dixie Belle has a product called White Lightning that is great for this.
Take one of the cabinet doors to the paint department of the home improvement store and ask them to select paint/stains and other finishes and application tools that will work for your kitchen. They have the best selection, the most up-to-date materials and most important, the most informative sales staff to get you what you need for a professional job.