Which direction does the front face? If it's west you might need a paint or varnish with UV protection.

It's not hard in skill , only put on a little at a time and use broad movements. Instructions are on the tin, or the Internet.

@lisaangwin I find gel stain is easier to use and yes you still need to strip the door first.

Black will really make it get hot & perhaps fade too. Please just do not paint it gray. I would check with a painting expert & use the method they suggest to protect it from the strong sun. The way it is looks neat. Kind of cinnamon color.

Scientifically, blue is the colour that fades the least. You still need a high quality uv resistant brand, though, to stop cracking and peeling.

I think a high gloss peacock teal/blue would look good and add some needed color.