The best paint for an older deck depends on the material and whether or not your deck already has a coat of paint. Generally, if your deck already has paint on it, you should choose the same type of paint when repainting the deck. For example, if an old deck has oil-based paint on it, stick with oil; if your deck has water-based paint, choose water-based paint. 

Whether to paint or stain a deck depends on your personal preference for appearance and budget. Stain provides a natural look with a range of undertones, is typically less expensive, and may only require one coat, but it does not last as long as paint. Paint offers a sleeker finish with a virtually unlimited color palette. Both options will protect your deck from outdoor elements like rain, snow, and general wear and tear.

Staining a deck with a rag is typically a better option than using a brush, as it helps the stain penetrate deeper into the wood. However, both brushes and rags are best reserved for detailed work because using these tools on an entire deck can require tediously crawling around on your hands and knees. A pad applicator, sprayer, or roller are preferred alternatives to applying stain over the majority of a deck. Use a rag for railings and other detailed work, and let the wood soak up as much of the stain as possible before wiping away drips or pools.

It's okay to walk on a newly painted deck after about four to six hours as long as the weather has been dry. Be sure to wait at least 24 hours before you place any outdoor furniture or grills on a freshly painted deck, though.