Hey,
So I will have to sit the UMAT in a couple of years but I have no clue on where to begin my preparation! :/ can somebody please advise me on something to get started with? What should be one of the few things to start with?
Thanks 
Here is the best advice, don't prepare yet. Too many people have run put preparation material since they started so early. UMAT successes takes time, you should aim to
- read complex books
- play logical games like sudoku and chess
- try debating
- attempt puzzles online
- in general, try to empower your focusing skills
You can do well in the UMAT of you just practice day to day logical reasoning and do the above. Don't start practice exams until atleast year eleven. You should start doing practice exams when your are completely ready. Take it easy for now and you will be fine.