I think that women are sometimes more conservative than man in some areas, specially money, investments and financies.
Man are more adventure type but woman mostly stay at home and care about child, paying bills, worry about security etc.
So, How to motivate women to use Bitcoin?
Don't talk much but show something concrete and prove that Bitcoin can be useful for her.
Every one is looking for money. As money is the primary need of everything, everyone is looking for ways to earn money. Btc forum is one of the source to earn. Woman Just need to made aware if BTC's existence. They would carry this out.