When you are coming up for your Gybe there are a couple of things.
First bring your back foot out of the back strap and move it forward up the board so it sits in the middle.
Carve the turn, as you come out toeside it feels as though there is a "dead spot" - where your kite is not generating power lasts a split second - at this point (using the bar as a kinda bar support) quickly whip your front foot out put that in the middle of the board and slide your back foot in where your front foot was.
Don't worry about getting your feet in the straps to begin with in fact i find riding with back foot out a great way of getting better upwind.
Whilst on the inward tack shuffle your feet around to get them in the straps.
Laurie has written a very comprehensive article about gybing that makes far more sense that me its here
www.seabreeze.com.au/Articles/Kitesurfing/How-to-gybe-a-surfboard_2165971.aspxThing to remember the most is to get the movement in your head, imagine yourself doing the gybe as your walking about the place.
Parctice is the key like most things kiting once you suss it you wonder why you never managed this in the past.
Good luck...
