Some general "observations" not directly related to anything scientific:
Males seem to be more vigorous, not always
Males usually show first, not always,
Males almost always are my favorite "lookers" before finding out their sex. Meaning I usually favor the looks of the males over females if I don't know the sex. ("please be female, please be female" almost always turns out male..)
Males seem to stretch a bit more, have sturdy stalks, like not round but the ridgy kind.
All of this is completely tossed out the window as soon as you find a female that falls under any of these.