As a newbie, I'm thinking 12-18knots on a 12m kite.
Anyone got any thoughts?
what are minimums to get a 12m going? when would you consider swapping to a smaller kite? 20knots+ ?

G'day Andrew - there are many factors to consider in regard to your query. Your weight is probably the biggest factor followed by skill level etc...what ever you are comfortable with...
Check out the forum archives - there should be plenty of this info there.
Good luck.