To become a Mechanical Engineer, you will have to first get a bachelors degree from NITs,IIITs,GFTIs, IITs etc and the admission criteria varies accordingly like if you want to get it done through above mentioned institutes then you will have to crack IIT-Jee exam with decent rank and if you are interested in private and state colleges then also the procedure varies. But as per my view, better to get B.Tech in ME from decent NIT/IITs and once it is done appear in Gate exam as this would be giving you dual benefit like you can either choose to go for higher studies or PSU recruitment.

Hope this helps!!!