Basically you have to grip the ball perfectly. Most offspinners have long fingers. When you want to reduce the spin you have to reduce the distance between the forefinger and the middle finger to vary it. The most important thing is the organisation. For anything to survive and then thrive, you have to organise it well.
Money is also necessary.
I remember the recent women's tournament in Chennai, the CricInfo Rani Jhansi tournament. There have been lots of good women's cricketers. Things have to happen at school level. I've seen quite a few of them, Eduljee, Shanta Rangaswamy. I remember them playing against West Indies at Chepauk.