Just focus on making the best decision possible with the information you have. Get your money in with the best hand. I have these same problems you speak of online. I am less disciplined online and often push my chips in when someone comes over the top of me. I find it helped me I took a little extra time to make a decision when faced with a raise online.

Do you have more trouble online or live?? When I play live for some reason I am able to make bigger laydowns, usually from the tells that I pickup from people and instinctively I have a better feeling of just "knowing" I am beat.