Inspect and Prepare the Paneling
In some instances you may be able to remove the paneling and paint the walls directly. But often paneling was installed with both nails and adhesive, and you could damage your walls if you try to remove the paneling. Also, in some cases the paneling was placed directly on the wall studs with nothing behind it.
When you're ready to start painting, make sure that your paneling is made of solid wood. Some paneling actually consists of a vinyl print that simulates the look of wood. To check, sand a small area on the wall. Vinyl coatings come off quickly, revealing the pressboard underneath. If your walls have a vinyl or thin veneer finish, you'll need to take extra care when painting them.
Another point to consider is the texture you want your walls to have. If you want a smooth finish, you can fill the paneling grooves with wood filler, a time-consuming job, or hang a liner over the paneling and paint the liner. Otherwise, you can simply paint the paneling for a look of added depth and texture.