Some moments ago I blundered a rook when under attack of a knight and thereby loosing a match against a higher rated opponent while being 2,5 point ahead. 
I have now attached a memo in maximum font size stating: "opponent move: checks/captures/threats" in eye-sight next to my computer. Hopefully it will help.
Best advice I've had to date is: 'when you think you've found a good move, stop, and look for a better one before playing it.'