I followed CNKS's advice - except for the final coat.
I love the epoxy primer, it just FEELS better than any primer I've used before. More solid. I'll use that more often now that I've tried it. Expensive, but I'd say it's worth it.
The surfacer made all the difference in the world as well. it sands very easily and quickly and makes a huge difference on the sheet metal. Smooths out all sorts of little marks - I'd call it mandatory on sheet metal. Especially because it's relatively cheap.
Where I went astray from his advice was with the final and most important step - the paint.
Problem is I simply couldn't afford the good stuff.
I know I probably would have been happier with it - but the tractor I'm working on is a 4H project - so I've got kids painting - and it's all new to me as well.
I've sunk all sorts of money into the tractor already - and I know the common logic is "don't cheap out now" - but... business is slow!
I couldn't justify spending a ton of money on paint I didn't even know how to spray (first time with a sray gun).
I settled on the valspar restoration series paint at TSC. I cringed doing it - but, it just made much more sense for me. It's a little over 50 per gallon. Not cheap, but could be much worse.
As it turns out - I'm very happy with the results. And I'm very happy that it's "only" 50 bucks a gallon as I needed two.
I could have done it with one if I knew what I was doing - but between the kids and me messing up - (drop cloth dropped onto wet tank - runs in hood that we disasterously tried to wipe out - etc etc.) We had to paint a few things two or three times. Whole lot of spilled paint too.
Plus a lot wasted in cleanup.
With hindsight I would have gotten EVERYHING ready for paint all at once. Instead we did it part by part - probably lost at least 10-20% of the paint that way - being left in the gun & wiped out.
Keep that in mind if you go for $200+ paint!
Wish I could tell you how the paint holds up, but we're just finishing up the tractor now. But I'd trust what Andrew said about it.