Try using a piece of pva foam squeezed onto the hook or a small pva bag the size of a golf ball. Also when casting use your line clip or stop the spool just before the rig hits the water. this will cause the hooklength to straighten out. Also sometimes a small piece of Kryston Heavy Metal putty on the hooklink, a third the way along from the hook end, will help the rig kick out straight when settling on the bottom.
I can guarentee you this will work, because i do it every time i cast and i never have tangles.
all the best mate