The first and the most important step is to decide what type of company you are aiming for. Start by making a list of them! For eg: Amazon, TCS, Adobe, Wipro, Amdocs etc.
Learn a Programming Language: One of the most important things to start with is to learn & become familiar with a programming language like learning an OOPs language.
Learn Data Structures & Algorithms: After learning a programming language, it’s time to get into the world of coding with help of Data Structures & Algorithms! Explore all the different data structures like arrays, linked lists, stacks, queues etc along with the operations that can be performed by them & gradually move on to advanced data structures like Trees & Graphs.
Focus on CS Core Subjects: Along with DSA, you need to prepare for CS Core Subjects like DBMS, OS, CN etc. For someone who is from a non-CS-IT background, these topics can be a saviour in cracking the interviews.