Staining my Deck
If it's painted, be prepare to sand it to death. You can try a full strength paint stripper like "Dad's" that can be found at your local hardware store...be extremely cautious with chemical strippers though. I am hesitant to recommend professional grade products we would use, but you can try a sodium hydroxide stripper which would probably take several applications at your own risk. You'll then need to nuetralize the stripper on the wood before applying a stain using either oxacilic acid or citric acid. Then, you would need to allow it to dry (check with a moisture meter for less than 12%) and apply your new stain...assuming all of the paint comes off cleanly. Be prepared to use a solid color stain to get a good look.
For a good solid color stain I would recommend cabbots, semi-transparent I would recommend Ready Seal.
Good luck with your project...there are many variables in what you want to do. I hope some advice will be helpful.