All good paints have a system. i.e. Imron, PPG, Jet Glow or Rustoleum.
Don't cross mix systems. Follow their instruction for metal prep. prime and final coat.
Professional painters mix and have their favorite system but as a rookie I follow the directions. Good painting is 98% skill and 2% luck.
I was painting an aileron and when finished a bird flew in my hanger and pooped on my project. Took that as a message from above and let the pros do the painting from then on. I'm now a spray can only guy.