If you want to tint the neck to give it a vintage sort of feel or just because you like the color, then go for it! But first make sure you sanded it down fine. On my projects I usually go to 1500 or 2000 for good measure, but that's because I'm a meticulous perfectionist- but 600 or 800 should do. I don't think sealing the wood is necessary, since it's only a gloss finish. I take it that you'll be using a spray gun because you bought a compressor. If you are using a gun, if this is your first time painting, then when the knob is vertical (for up and down spraying), that means your spray fan will be horizontal. If your knob is horizontal, then it's for side to side painting with a vertical fan I believe (check instructions). Ok spray time!
This is how I would do it:
1.) LIGHTLY
MIST the area with the clear. Mist, don't coat it.
2.)Wait 2 minutes
3.) Spray your first coat in a vertical or horizontal direction (pick one), but keep in mind you'll be spraying again so don't coat it all the way
4.) Wait 5 minutes
5.) Spray your second coat in the opposite direction
6.) Wait 10 minutes.
7.) If you feel like you need to coat it again, then wait 15 minutes, then spray one more time.
IMPORTANT:BE PATIENT! Don't rush when painting and make sure you wait between coats. If you do, you'll drip.
If you're painting with a gun, then the resulting surface should be smooth enough so you don't have to sand it. If you do want to/must sand, then:
1.) Make sure it's completely dry! (But then again, Nitro never cures
)
2.) Wet sand starting with 800, 1000, then 1500.
3.) Clean up the dirt off
4.) Use Carnuba wax (Car polish) and buff your surface till you can see your reflection
Try not to sand through your surface.
The longer/finer you sand, the shinier the result is.
I don't know if this will help, but these are the steps I would take.
Good luck!
i don't have any experience, i'm not familiar with that new term "PATIENCE" 
and i'm scare to mess it up with the neck, i mean, the neck wasn't cheap for me, and i really don't want to screw it up, because i really like, i think i'll start using de gun with a guitar body before a one piece maple neck.