Dear Jerome:
bienvenu sur ce site!
Mini-miles are indeed hard to get and the seats most likely to be sold 100% through bucket shops (deeply discounted tickets). Hence, you should consider booking a "higher" class of ticket. I found AF to be very co-operative and flexible in redeeming. It is one of the few airlines where you can pay with miles for tickets for third parties - I tell you, that's a real treat. Their rules on non-expiry of miles are also very beneficial and their redemption rates not unreasonable. In any event, you should always aim to book "holiday routes" at least three to four months in advance.