Start attending preparatory courses of the Institute, which is going to arrive. Despite the fact that the courses are expensive, the result will not keep itself waiting long. Typically, these courses are teachers who are on the staff of the Institute. They will prepare you precisely for the jobs that will in the entrance exams of the University. Do not miss a visit to courses or else you risk not to pass the test. The number of days depends on how much time is left before the entrance exams. If time is running out, be prepared that you will have to spend a few nights in the week and one day off to prepare for exams. If you started your preparation in advance, it may be enough for a couple of days a week usually in the evenings.
If your budget allows, hire a tutor. Best of all, if you manage to negotiate with one of the teachers of that University in which you want to do. He individually explain in accessible language how to solve those or other tasks and examples. You can ask him incomprehensible questions that will receive clear and intelligible answers. Also, this teacher knows better than the program of his University and the "slippery places" in the entrance exams. He can tell you about them, which will greatly increase your chances of admission to students.
Prepare for entrance exams on their own. For that you need the guidelines of the University, you decided to take exams and its collection of tasks. Typically, each institution has an archive of those tasks, and examples that were in the entrance exams of previous years. The Institute prints them in the form of small booklets that can be purchased for a small fee within the walls of the institution. Your task is to find and purchase this collection. For successful passing the exams you need to complete all the tasks you will find in it.