Identify them early.
Find an easy end pattern that works well with your skills and abilities. Many players get in trouble because they leave their comfort zone. If you watch some of the great players, it is NOT that they make everything seem so simple - it is that they KEEP everything so simple. Remember that.
If you go back and watch some of the evaluations that I have posted on Veoh and youtube, you will see that I always tell the player to look at what is there and what isn't there. Do that after every shot. Plan and then execute. Always re-evaluate.
There are different end patterns, but the best and most reliable are the ones that have balls that connect together with stop shot position.
I would recommend that you take some video of yourself playing 14.1. I don't need a large run on tape - in fact I want to see the mistakes that you make on a regular basis. Most of the time I watch players shoot away key balls much too early - or they shoot off and eliminate balls that will make their end patterns easier.
This could or could not be the case.
Take the video - send it to me and I will take a look at the way you are clearing off the table. I guarantee you that we can identify whatever it is that is holding you back.