Are you using your right hand doing anti-clockwise suicides? (from your point of view)
if so:
Hold the position of the suicides out to the right, wait until the free end/stick is coming round on the left and you are pulling up
While you pull up also pull it back and around to your right side. You might want to step forward at this point, once you can do it moving a bit you can stand still or keep the diabolo still while you walk round.
Wait until the free stick is at the lowest point before doing most of the turning or it can hit you. The right stick must rotate with you while the tip does the same movement around the diabolo (you may find it is the diabolo going round the stick at this point
Turning back the string is spinning clockwise and you need to wait until it is at the top, you may find you can get a feel for the timing and turn back after a whole spin the other side