Engine Compartment

I'm wanting to paint / freshen up my engine compartment. It will be rattle can job. My question is this.. Do I just "scuff" and spray..? Take down to metal..? If scuff and spray, do I really need to primer..? There are a few small spots / areas that have surface rust or metal showing...but minimal.
This will be a temporary fix as the whole car will get body work and painted by a professional...but I'd like it to look nice and last as I'm not sure how long "temporary" will be. Thanks in advance..!