Every student have a dream to become a ISRO scientist. And to became a scientist there are steps which they have to follow from the initial level. 

So basically who is willing to become a scientist they need to have PCM (Physics, Chemistry, Math's) during 10+2 education level. Most important thing is that they should be strong on these concepts, good knowledge makes them more eligible for further steps.

After passing the school level with 75% or more, student can enroll in one of the many engineering exams like JEE mains and JEE Advanced. These exam actually are the best for the students to test there skills and ability to find themselves. 

One thing is that there are two choices for them if they think these engineering courses are too long so they must apply to the graduation courses regarding this. They can persue to BE or BTech in courses like Computer Science Engineering, Mechanical Engineering, Electronics. There are many colleges in engineering felid they can choose.

Now we are in stage 3, so after completing BE or BTech degree, students need to enroll in the exam name ISRO Centralized Recruitment Board (ICRB). The basic requirement of this exam is that students should have the degree in BE and BTech in the field of their specialization with the minimum aggregate of 65%.

After clearing the exam, the shortlisted candidates should appear for the written test and an interview round to join the organization successful.

Now there is another route for those who completed their Masters (MSc. ME, MTech) in related specialization. On completion of the degree, some of the MTech courses like applied mathematics, instrumentation etc.. For applying directly to the ISRO they need to give a test and after clearing they called for interview, with clearing this the students can secure a job as a scientist at ISRO.

So these are steps student should follow and if they make decision they can do and achieve.