There's other ways to get it done, but this way i think is your best bet being a n00b to "woodworkin".
If it has any paint or stain on it you need to sand it. Use 150 grit then 220 grit. You want to take the shine off. Making it dull. Then prime it. And then use 0000 steel wool to smooth it out. ( very lightly!) Careful not to sand the prime off. Also when you do spray make sure its an area that's dust free. Use the same brand paint and primer and clear coat. or else it will crackle...(i found out the hard way.)
Don't over spray it. Paint with nice smooth flowing action. If you want to test your hand on a scrap piece of wood to get the flow right and to get the right distance you need to be away from the material.
Spray paint a coat then let it dry hard. Use the steel wool again to smooth it and get rid of the dust that you will most likely have. Then repeat 2 pr 3 times. Then use the clear. Same process with the steel wool. Clear coat it 3 or 4 times to make a good coat. Then you're done.
And pix are required.
[youtube]http://www.youtube.com/watch?v=CReRbqCBj7I&feature=related[/youtube]
^^^ The first 6 minutes of this video shows you how to go about sanding it...
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If you want to spray it in camo...then this is a good video...he uses actual leaves and stick and brush. it came out great too...
[youtube]http://www.youtube.com/watch?v=3q9YYy3O3m8[/youtube]
and if you are doing it this way..don't worry about dust.