You can apply for the Polytechnic entrance exam after completing the 10th. The eligibility conditions for this examination are as following:

Polytechnic entrance exam eligibility:
The applicant should have completed 10th with minimum 33% marks from any recognized board of India.

You can apply for following good diploma courses:

Diploma in Civil Engineering (Polytechnic in Civil).

Diploma in Mechanical Engineering (Polytechnic in Mechanical).

Diploma in Electrical Engineering (Polytechnic in Electrical).

Diploma in IT Engineering (Polytechnic in IT).

Diploma in Electronics and Communication Engineering (Polytechnic in ECE).

Diploma in Computer Science(CS) Engineering (Polytechnic in CS).

For your reference here I am giving the list of some good polytechnic colleges:

Bhadrak Institutes of Engineering and Technology, Balasore

Bharati Vidyapeeth's Jawaharlal Nehru Institute of Technology, Pune

Dayanand Sagar College of Engineering, Banglore

Ghousia Polytechnic College for Women, Banglore

Government Polytechnic College, Amravati

Government Polytechnic College, Ahmedabad

Hindustan Academy, Banglore

Meera Bai Polytechnic College for Women, Delhi

MEI Polytechnic College, Banglore

Nirma University of Science and Technology, Ahmedabad

Kalpana Chwala Government Polytechnic for Women, Ambala

Polytechnic for Women South Ext, Delhi

Rural Polytechnic College for Women, AhmedNagar

Govt. Polytechnic College for Women, Haryana