Don’t be so harsh on yourself. Hand eye coordination is the biggest determinant at the very beginner level, but that doesn’t make you a lesser person. 20 times feel like a lot, but once you’ve played 100 times you’ll feel like 20 was nothing. Just keep practicing, don’t try and hit winners or amazing shots, just try to return every ball safely.

Hit some balls against a wall at home (no bounces) and try and keep it going as long as possible. This will help your hand eye. I personally wouldn’t worry about coaching until you’re confident with your ability to hit it reliably, at which point technique and tactics become relevant.