I could say buy a Flysurfer, but here is a trick I was doing with a Liquid Force Havoc while kitesurfing last month.
This is almost the method for self launch, but with my wife assistance
I place the kite already in position to be launched at the edge of the window. I put a bag full of sand on the tip that is on the ground.
I go and get my bar, I hookup the safety and the loop.
I put some tension in my lines and when I am ready to launch I ask my wife to remove the sand bag from the tip, and she walks away (upwind) from the
kite.
It's easy for her, and I found it was pretty safe for launching.
For self launch, you could almost use the same method, and use fold the tip before putting the sanf bag on it. So when you pull hard on the kite, the
tip unfolds, and the sand bag gets away, and the kite starts flying.