So, you want to stain your fence or deck on your own? Here are some things you will want to have. If you want to do it right and it was done before or its "new" and wasn't done right away and months have passed, then a pressure washer is an absolute must. If it is brand new, then pressure washing won't really be needed. A sander or sanding blocks are a good tool to have in order to smooth areas out as needed or after pressure washing. An electric drill or hammer is good to have on hand in case some areas need new screws or nails. A stain brush along with a hard bristle brush are usually needed. Extension polls are great to have so you're not constantly bending over. A bucket, Roller, paint knap, and screen are something to have. Although you can skip these and just use a brush, but it can take a little longer to apply.
Rags may be needed depending on if you're using a wiping stain or not. Paint thinner or mineral spirits are good to have on hand for cleanup. Tape and masking paper are also great to have to help with drips and protect surfaces around the area to be stained. Cloth drops are great in order to protect the ground. If the surface was previously stained, then you'll need some stain stripper and maybe even some wood brightener if you'd like (This is where the hard bristle brush come in). And then optionally a sprayer to help apply the product. Also, one last thing that's convenient to have if your spraying are pieces of cardboard in rectangular shapes called shields. They can also be purchased already in rectangular form from Home depot, Sherwin Williams or most hardware stores. For learning purposes, I did add a few extra tools and supplies that are handy to have but this is all you should really need in order to properly stain your fence or deck. Last thing you'll need is the actual stain of your choice!