Wait for all this rain and humidity to pass
The durability/quality of any paint job is primarily dependent on the prep and secondarily, the quality of the paint used.
1, Clean the surface with simple green cleaner (it's the cleaner often used to clean BBQ grills--sometimes found in that section)
2. Sand with 80 grit
3. Wash and clean with TSP (trisodium phosphate)--Home Depot/Lowes
4. Sand with 180 grit
5. Wash with acetone, let it dry, and rub off any old paint that has lost adhesion with a scotch brite pad.
6. Prime with SEM self etching primer (Amazon.com) to any bare metal areas
7. let it dry
8. Apply paint primer of your choice (I'd use an oil based enamel) A good option would be Valspar Tractor and Implement primer. Amazon.com has the best price
9. let it dry
10. Buff with scotch brite pad
11. Apply paint primer of your choice (second coat)
12. Let it dry and buff with scotch brite pad
13. Mix Valspar 4625 Enamel Hardener (amazon.com) with Valspar Tractor and Implement paint (sears.com) per instructions
14. Apply first coat and let dry 4 hours
15. wet sand with 320 grit
16. Apply second coat.