I'M A CLASS 10 STUDENT AND WANT TO PREPARE FOR RMO. CAN YOU SUGGEST THE BEST WAY TO DO SO.

1. Don't ever be intimidated by the problems. You get scared, you lose. I learnt this the hard way in INMO - I couldn't solve problems in the test that I would have easily solved at home. Dealing with pressure and expectations is difficult, but don't let it get to you during the test.
2. Read the Art of Problem Solving Part 1. Many of the strategies there are extremely useful; there's a reason it's so popular. Wishful thinking and 'keeping your eye on the ball' are two of my favorites.
3. Every RMO problem is killed by one key observation/ fact. Get this, and you're pretty much done. Examples are, a certain quadrilateral is cyclic, this expression is a perfect square, and so on. Not very difficult to see, but not obvious either.
4. You only need to solve 3-4 problems out of 6 to qualify. Make significant progress in one problem and you'll get more marks than had you spent trying all of the 6 problems. From what I've seen, you get either 0,1,2 or 6,7,8 or 15,16,17 marks based on your progress. This makes it crucial to focus on the problems you know you can solve.
5. Geometry is important, there are generally 2 questions every year. It's pretty fun too. Don't be afraid to bash (try big computations) if you have the time. Some questions require patience. A lot of it.
6. Inequalities are dead at the IMO level (almost) because of calculus based techniques like the tangent line method, uvw, pqr, Langrange multipliers, and so on. But, you will never need to know any of these for RMO. Stick to your basics, such as the Power Mean, Cauchy Schwartz and Chebyshev inequalities. I guarantee you that these will be enough for now. Recently however, there are fewer inequalities being asked in the RMO.
7. Number theory is useful. Always look out for an application of Fermat's little theorem or some other congruence if asked to solve an equation in natural numbers.