Painting axle

I have my front axle removed and would like to paint it while its out.

So far I got all the grease off and scraped it with a wire brush.

I dont want to paint it and watch it peel off not too long after, can anyone tell me the best way to get the paint on, and what type of paint to use. Do I prime it as well??

Yes prime anything if its down to bare metal. Be sure you cleaned it thoroughly with degreaser or at the least soap water. If you have money laying around I'd suggest POR-15 since it will hold up great. Otherwise just spray very thin and do several passes so its not just thick and soft.

I did my front with two rattle cans of black and one orange Rustoleum Enamel. Its been two months or so and its still holding up great. I expect some minor chipping from rocks and just debris. Its just a rattle can job so it won't cost me much to touch up...

Check out Epoxy paint in a rattle can. Stuff works awesome!