Hello,
It's a good thing you are interested in Maths. Often times, students don't like Maths and that makes it harder for them to learn the subject. If you feel like you are weak, it means you have to work on your basic concepts. Start from the very beginning and then move onto difficult topics. For example, in order to master Differential equations, you need to be good at Differential and Integral calculus, as well as well practiced in integration and differentiation. Refer to NCERT and R.D Sharma in order to strengthen your basics and then move onto tougher books. Also, keep practising as much as you can. Solve problems, use different methods and above all, ask questions. Make sure to clear your doubts. Don't stall them onto the next day. Solve and work on your doubts as soon as come across them. With practice, over time you'll get better. Hope this helped. Good luck.