i am persuing b.tech in electrical engineering i want some tips to prepare for RRB exam.

Firstly understand the exam pattern of RRB Exam.The Computer Based test (CBT) will carry the maximum weighatge of 100 marks and composite time of 90 minutes You must know the subjects that come under this exam.It consistes of sections like general awareness,Numerical ability/quantitative aptitude,Reasoning.make an appropriate time table. So that you may get an idea that how much time need you need to give to a particular subject.Regularly make notes for  Exam, so you can easily understand and revise the previous topics. practice as much as you can.Previous year  old papers helps a lot to get an idea that how RRB sets examination paperYou can also buy books like:
Railway Recruitment Boards RRB (Non-Technical Cadre) 2016 by arihant experts.
Upkar Railway Recruitment Board Examination (Khanna & Verma)
Arithmetic (R.s Aggarwal)
Verbal & non verbal Book (R.s Aggarwal)
Lucent's general knowledge

Be positive..good luck:-)