First of all, get yourself some CA (cyanoacrylate) glue as you will need it to glue both types of parts.
Painting, as always, depends on the type of paint you will use. My experience is based on using Tamiya acrylics
PE - if using acrylics, you will need to prime PE parts. I use a lacquer based primer for this but even when using primer I like to drag the PE part over sand paper first to give the paint a better chance to grip the very shiny PE. Not really possible with tiny parts.
Resin - be sure to wash the parts in soapy water and thoroughly rinse and dry them. I use an old toothbrush to clean the parts. These parts are often covered in a mould release oil that will cause your paint to flake off if not dealt with. Once dry, I have painted resin both with primer and without and found no real issues either way.