Blunders in daily games
Sit on your hands
It depends on when I move. I should learn to never move while tired, because I am much more likely to just drop a piece for no reason (while thinking I'm clever because of some "deeper" plan that would work if only I noticed they could just pick off the bishop with their queen or whatever.)
And if I look at the same position while better rested, it seems obvious to me. Sometimes I almost make a move, realize I'm tired and have like 10+ hours in the game and decide to just move after a night of sleep instead.
There's a setting for daily games (maybe also rapid, blitz,...) to make a move but you have to confirm it afterwards. So make the move, then look at it, and you can revert and try again. Helps a lot to check your own move on the board before actually sending it.
I don't recommend this setting for quicker time formats though