Here's some pictures to describe how to prepare the resin parts. I guess most of modellers would find it's quite basic (maybe boring) but I want to start my explanations with the beginning......
Remove the excess of resin with a small saw (the best tool for small parts is a photo etched saw)
Start to sand the part with a metal file :
Then use a fine sand paper to ensure a smooth surface :
Clean the part with "dish soap" (or any liquid diswashing soap) and a teeth brush (please take an old one)
Brush the part to remove the grease residue.
Then rinse the part with still water and let it dry.........