A way to address this is to learn how to compare fractions and find common denominators so that two fractions can be numerically compared clearly. The worksheets on this page provide exercises to do exactly that, and they are good practice for the steps necessary for other fraction operations.
Addition is the foundation of arithmetic. If you practice the above-mentioned methods, it will improve your subtraction skills too. Apart from these methods, make use of math work books. Write down each number in the box and then use methods discussed above.