Abstracting Reasoning is a section of the UKCAT that is hated by students. There is no real way to learn it; either this sort of thing works for you, or it is a nightmare.
I, like many others, was in the latter category. First step is to not think what this has to do with medicine. It is a hoop you have to jump through in order to get to your goal. Think of it as an obstacle that needs to be overcome; a means to an end.
Now that we have the correct frame of mind, we need to practice. Many books for the UKCAT exist and they are generally quite good. I would recommend medify, which is an online tool. You may for it, but it is worth while if you want to practice. It tells you were you are going wrong and what you should be improving upon. It gives you the questions that you are not good at to get used to them.
Other than that you have to just power through this test. The people who did best in this were the ones who were calmest about it; whilst those that stressed out and were looking for intricate strategies to get through the UKCAT were disappointed with their results.