After doing this for over 15 years I find that the best method is to clean all parts with Wesley Bleche White and warm soapy water. This is a non-corrosive cleaner. Use this for nuts bolts brackets plastics circuit boards wire harnesses etc. It is by far the best cleaner out there.
For parts with mild corrosion I use a tumbler with walnut media. For certain metal parts I will finish up with novus 2 prior to installation. And Novus 1 for all plastics.