This was a favourite tactic of mine back when I was in my last year or juniors (and I was still fit, lol). I used to get very nervous at the beginning of a match, but I did a lot of 4 corner vs 1 corner, or isolation. My training partner would stay in the back corner and I would just clear to them.

Applying that to a game is great if you can do it. It builds your confidence because you know that even if you keep messing up all your other shots, that if necessary you can just keep hitting into that one corner until you relax. Also, it is very frustrating for your opponent because they can't seem to get out of that corner, so they start going for things and make mistakes.