Kel, I tried to use it on sidepanels for the RM250A I just sold. I ended up going back to ordinary spray enamel, so I could at least prime and sand. The fusion is designed to be sprayed with no need for sanding...on my old plastic parts they needed sanding. Worse, once you coat it, you must wait 7 days to re-coat.
I suppose it has it's place-plastic furniture etc., but you may want to sand and polish your plastics. This has been described here before, on other threads.
While I polish aluminum parts( working on two Bultacos, then a Rickman and a CZ), this is a tedious process to polish plastic. I gave up.
You could prep as you would for any quality automotive paint, but add flex agent, so it will flex with the part.