Take the finish off and go back to the original wood.
Progressively sand from 100 Grit through to 400 grit as a minimum to make it even.
Now it depends whether you want grain showing in you finish, if not you can use a grain filler, sand.
Primer bass coat, sand it.
Colour if choice (you can get spray cans of guitar finishes so you don’t need a gun)
Sand between finishes till you get a good colour
Sealant of choice.
Thats if you want a solid type colour - if you want any grain showing, it will be a different process