Hey Pankaj

To prepare for polytechnic first of all you need to check out it's syllabus. Syllabus for all polytechnic entrance is almost same. 

First of all you need to clear your basics and go through the Ncert for class 9 and 10 in mathematics and science. You may look for a Arihant publication books for your respective state. It is easily available on almost all book stores. Also go through the past year papers.

Feel free to ask any other query.