I am a student of 12th standard. What steps should I follow in order to get into IITs or NITs?

After successfully completion of 12th class, you need to attempt JEE main exam for the NIT college. You need minimum 120-150 marks to get any of NIT. If you want to get good branch then you need to score 170+ marks. For getting into IIT, you need to attempt both exam those are JEE Mains and JEE adva

If you want to get IIT/NIT in your native, you need to score high in IIT-Mains/Advanced. To score high in IIT entrance exam you need to put a dedicated effort. Practice a lot, keep make note of tips and tricks. Try to solve as many problems as possible. Take tests to evaluate yourself. Best of Luck!