If you are using an open grain wood yes use a grain/wood filler. However for solid colors on any wood I’ll use Min-Wax 2-part wood filler. Sets ups hard and is pretty much identical to auto body filler (bondo). Sand smooth and spray 2 or 3 coats of laqcuer primer. I get it in spray can form at an auto parts store. Sand smooth and reprime as needed. When done with this step your body should be level and smooth on all surfaces. Final sand primer with 320 or 400, clean it of all dust and dirt, rub down with a tack cloth, and start spraying your color.

If you can keep the dirt out of it spray 3 coats of clear, let dry, then sand level as you can without going through. I then spray 2 coats, let dry, then level sand again. I’ll repeat that as necessary. 

That looks about right, but I'm no expert. Nitro is a nice thin finish, but is very easy to sand through! 

I think @boo is the expert in finishing here. I'm sure he can give a few tips 

ill be painting a setneck guitar with the neck already glued in. I want a solid black color with a shiny clear coat….

after watching the finishing videos my thought is:

sealer

grain filler

paint

scuff (repeat until solid color)

clear coat, scuff, repeat until I have enough coats of clear…

then I move to flattening and polishing… does that seem right? I think I’ll start with a nitrocellulose so I’ll get a black and a clear coat…. I have a spray gun and a clean area to paint with ventilation.

am I missing anything here? I’m excited to finish this one