Hi Sunseeker,
Different people have different preferences but this is how I set mine up ...With the depower strap fully extended and the bar at your most comfortable kiting position (Usually about half way)...Your lines should be equal length at this point ...
This gives you the full length of your depower strap for depower ...
You still have a little room to power up with your bar but I reckon any more powered up than this and the kite just stalls...
I tie the lines to something solid and use my harness to hook in while checking these settings ...Also make sure your outside lines are exactly the same length so your bar will be at right angles to your lines (ie straight) ...Check this by pulling from the centre of the bar with tension on the outside lines ...The bar should stay at right angles when you do this ...if not, shorten or lengthen one of the lines until it is ...
Next thing try it on the water if it's not quite right for you then make appropriate adjustments ...
Hope this helps ...