tip 1: keep opponent in center as much as possible

tip 2: when your opponent is on your side, connect your near elbow and knee instead of opening it

tip 3: never hip(back) toward your opponent

frame your far arm to prevent this:

tip 4: far leg to shield and near leg to find opponent

tip 5: lift legs high for the guard, make you easier to turn

tip 6: never let one leg trapped between opponent's legs

to prevent knee cut, the keen should over the elbow: