Many students attempts all questions and able to get 45-50 out 100 some attempts 90 marks and get 60.Well..there is technique to write answers in university examination.Talking about engineering exam following things need to be considered while writing answers :
1) Pointwise or paragraph : Try to write answer in points.If you are very clear with the answer and knows everything about it,just write in points so that checker quickly judge the answer and give better marks for it.If you are not clear with the answer and knows only something about it than write in paragraph so that you can extend your answer with relevant and other information.
2) Make block diagrams where needed.for block diagrams use pencil.scale is optional,if you will scale it takes more time for making it,shape of block can't matter much,information inside block matters.
3) Write answer according to marks.if question is of 2 mark write very precise answer may be of 4-5 lines.if question is of say 20 marks write long answer with diagram,block diagram whatever needed approx 2 pages.
4) In Maths, even if you don't know question,try to attempt it.write some steps and try to solve that because you can get marks for steps too.
5) Don't waste much time in diagrams,try to make it fast.use scale as minimum as possible.
6) If you know 20% of answer and you have to attempt it,in this situation write information that you know in first 2-3 lines and last 2-3 lines,rest answer you can write about other information.
7) Time management is most important if exam is of 3 hours try to complete first 2 questions in first hour out of 5 questions.
8) Try to attempt all questions.if you don't know about answer,write something about that topic but attempt it.
9) what ever you write should be neat and clean,it should be readable.