i have just got a blade 3 3m whats the best way to tune it up

Just like any kite start in lower winds to play with brake lines,You have to be able to land kite by aplying both brakes in same time.To short brakes will make kite hard or not possible to lunch,to long You will not land kite.Note that both brake lines have to be same lenght. Power lines witch You shouldn't touch are the same lenght as well.In very strong winds You might find that brakes don't work as easy (like in lower) to land the kite.Now You just have to find what is working for You.I like to have my blades brake lines short,so they almost starting to brake the kite but still they don't brake the shape of a wing.Most blades need some brake input as it make kite turn super fast(that apply to larger sizes).You should be happy with Your 3m in 16-30mph depends on Your total weight and skills.
Enjoy Your flight.
Slawek

cheers 4 that bit of info it has helped a lot