So assuming you trust your partner, how do you even know what to send?
13 Women Describe What Makes an Attractive Dick Pic
Unless somebody has explicitly asked you for a dick pic or nudes, do not assume that pulling your pants down and letting them in on how your genitals are looking that day is a good icebreaker.
I like being able to see some background.
Erect is probably better than flaccid to hit it. This way you can emulate posing seductively, and I really like taking short videos sometimes.