First off make sure you want to paint it. The paint will be a pain to remove.
I have painted a few of my guns. I am attached to them and they will not be leaving me for a long time.
Paint wise. If you want a good primer go to auto parts store and get the self etching primer it digs in. Plus it is a light olive green so it can become part of your camo. For the black, I like the Rustoleum BBQ. Fusion also make a very good paint(wallyworld) Somthing you may think about is getting it parkerized. Not real expensive and last a long time.
Oh and one more thing. Be prepared to get fussed at. Many folks are purest and do not like people painting guns
Make sure to post up your picts.
If you thumb around the archives or check in the FAQ of the H&R NEF rifle forum. There picts of some. Beware of stimpylu32's advice he likes florecent guns
Lonny