use the appropriate medium. if person likes email, shoot them a email; if they like twitter, twit them.
ask a small question that is easy to answer. distill your big question into smaller ones that could be answered with a few sentences, while also interesting enough of an extension of their work they want to answer it.
ensure they haven’t answered this question before publicly (e.g., in a blog). answer question that shows you know what they’ve already said about it and how you’ve used it.
never ask to promote you (or imply that); they don’t have to do anything for you.
