Dear aspirant,

First you need to decide that what is your 1st preference between cat or gate. So if you want cat then you need to start by working in your English and then you need to focus on current affairs by watching the news or reading English newspapers.

Start giving mock tests for these competitive exams because without giving mock tests you won't be able to judge your accuracy , time management and your weak areas. So this is also the same case in GATE.