Flanking

To half-flank a creature you need to stay over 90 degrees of the direction a creature is facing which gives you a +2 to hit.

To flank a creature you need to stay over 180 degrees of the direction a creature is facing which gives you advantage.

Focus
If you are within more then 1 enemies threat zones, each round you can declare a target that will be your focus and you can change the focus with a reaction, said target cannot get an aoo if you move inside of his threat zone so if you are moving throught multiple enemies threat zones the rest will be able to attack you - given you move more then 5 feet but that one won't be able to.