I am thinking about painting our exsiting kitchen cabinets instead of replacing them. They are pretty average size and stained a medium dark color with what look likes a glossy finish, although it may be a semi-gloss finish. They are aobut 25yr old cabinets but still in good shape, they just need a bit of sprucing up. Is there anything special that I need to do to them as far as prep work goes since these are stained and not painted? Or can I just sand and prime and paint to my hearts content? Any help would be appreciated.