I like the punch-down fold for insertion.  And I've found that if I face the punched portion DOWN during insertion, it opens easier.  (My less successful attempts faced UP.)  Since my finger is kinda in there anyway, I slip it in with my fingerprint facing the punch and swing my finger so the nail side opens the vaginal wall just enough to let a little air in to fill the cup and open it.  Ta-daaaaa!  Even the notoriously difficult Diva opens easier that way.  :o)