Half guard becomes dangerous when you treat passing as a race to chest-to-chest pressure. The safer first goal is to win the knee line while your opponent is still deciding which guard to build.
Use your first connection to turn the knees away from the direction you intend to travel. The pass begins with alignment, not force.
When a strong upper-body frame blocks the obvious direction, keep the legs pinned and circle toward the side with fewer connections. Do not drive into the frame they already built.
The back-step is useful when the trapped leg is already shallow. If your heel is still caught, turning away gives the bottom player the half guard they wanted.
Redirect, circle, or back-step according to the connections in front of you. The best pass is the one that prevents half guard from becoming established—not the one that escapes it late.