Yep more practice but not more wind. In 10-12 knots you'll have to dive the kite quite agressively down through the centre of the window to get going and don't try turning upwind until you're planing well especially until after the first up stroke.
In 12-15 knots DON'T dive the kite aagressively or it'll just drag you off the board, a shallow sine high up is better, really you just need to nudge the kite down into the window and towards the edge and you're allready going.
About getting on the board some people swear by trying it behind a boat but I never did.
Imo the best way to get the feeling of getting up is not to get up at all
really at first. Sit in the water with your board on your feet and your legs bent so the board is under your bum, dive the kite a little, if this isn't enough try a deeper dive. Don't straighten your legs and the kite will just pull you out of the water sitting on the board really easy and you'll be going downwind sitting on the board, straighten your legs to stand up and turn the board slightly upwind, smile because you're kiting, then fall of, this is a very important part and something of a tradition for all of us here on the first run
When you've done this a few times you'll get the feeling of starting pushing out with your front foot to start the board off downwind then carving the board upwind as you pick up speed.
At 70 kgs I wouldn't try the 16m Rhino in anything more than 15 knots until you get the hang of it if I were you.
When flying the kite don't pull too much on the bar because the power is transmitted much better to your body through the harness and the kite'l fly better, just use the bar to steer powering up just a little. Powering up too much will kill the airspeed and power of the kite in flight, depowering a little will help it on the up stroke.
Have fun and let us know how you get on.