Greetings !!

Currently You are a diploma holder. So you may apply for notification demanding educational qualification as Diploma in Public sector Undertakings. If you are looking career in Technical field, i recommend you to have a look at the websites of all the Mini Ratna, Nav Ratna , Maharatna companies like BARC, ISRO, SAIL etc. Every year these companies come up with notification. You need to clear the written examination , questions comprising of Current events, Quantitative aptitude, Reasoning alons with your subject knowledge . Besides, Railway recruitment board also recruits candidates. But if you are preferring clerical jobs then you may appear for SSC CHSL, SSC MTS and other notifications by your native state.

As competitive exam demands 100% dedication for exam preparation. You need to dedicate at least 3-4 hours for your preparation. Don't wait for the notification not come,  I suggest you to practice the questions from R.S Agarwal books relating to quant & reasoning. Follow adda 247, Wify study, GK Today for current affairs, Read News paper daily for improving English language. Definitely you can clear the exam in one go.

Wish you Good Luck !

Thank You!