OK...
Give the whole Guitar a scuff sand with 340 grit sand paper (you can also wet sand with 340 wet and dry, just dont drown your Guitar

)
Then apply a coat of the new finish and let it cure, should be hard after a few days.
Give this coat a light scuff sand with 340 grit, dust it down and apply another 2 coats.
Let these coats harden, then very lightly scuff sand with 800 grit and apply one more coat.
If you are super patient, you can leave it for 21 days and then give it a cut and polish to get a nice gloss happening.
Or, you can give it a week and build and play.