When refinishing furniture, it's important to first strip the old finish off the wood. This can be done by either using a chemical stripper or by sanding off the old finish. However, if you don't want to strip the old finish off, you can use a wood sealant instead. A wood sealant will protect the old finish and will also help to seal in any new stain that you apply.

It's actually pretty simple. You can use a wood conditioner or a wood primer to help the new finish stick to the old finish. If you're using a wood conditioner, just follow the instructions on the bottle. If you're using a wood primer, put it on in thin coats and let it dry completely between coats. Once the primer is dry, you can paint or stain the furniture however you like.