I used acrylic spray paint for my first build and am pretty happy overall. I added some acrylic flakes in a bottle from a craft shop which proved to be really time consuming (lots of waiting for paint to dry and sanding) but gave a pretty cool finish. I used automotive acrylic spray cans from a car shop and found the primer to be excellent in terms of being self levelling and filling any imperfections in the wood. It sanded down to a nice smooth finish for the paint. Clear coat over the top was recommended to me - I put on about 12 thin coats and sanded with steel wool. I am in North Queensland and it is pretty humid, but don't go less than 24 hours between coats - I got greedy and tried to apply 2 coats in a day and had to sand right back because they didn't adhere properly - cost me another can of paint and a lot of time.

Same for the tru-oil, min. 24 hours between coats before sanding up here. I wanted a really glossy finish - took 30 coats each side of the fretboard sanded with 000 steel wool each time to get the finish I wanted. All the time is in sanding, took about half an hour each time to sand, putting a coat on only takes a few minutes. Don't put too much on your fingers or you get imperfections and watch for runs. Lots of thin coats seems to work much better. I also tried using a rag, but just using your finger seems to work much better, you get a lot more marks in the finish even with a very fine cotton rag.