If they're running at you: Short Hop, Down air. It auto-cancels so you should be safe upon landing, not to mention that you can get some pretty sick follow ups if they don't tech. Otherwise Up-tilt is useful for if they're getting in your face from above and like you mentioned, down tilt for popping them up. A key combo is D-Tilt -> Jab -> Grab and follow up any way you see fit.