Unlike cast parts, there is no mold release, but I prefer to give printed parts a quick wash in dish detergent just to wash off any hand grease/oils before priming. May not be absolutely necessary, but it doesn't hurt.
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No washing on my part.
I prime them as well, using Tamiya rattle can spray. Just enough for a light cover. Then acrylics with an air brush for colors. Never had a problem with this routine.