i used to make mistakes like that, and they cost more than i was happy about.

Rule 1: Never use instant action buttons
Rule 2: When betting/calling, always double check the amount

Edit: My most memorable mistake of this kind was with 22, I intended to limp and fold if i didnt catch a set. The player before me pushed all in and i didnt realise. So i called it and nearly shat myself. I punched a few things, then looked at the result. I'd doubled up unimproved, turns out the idiot had pushed with 92.