It is advisable to apply for as many as entrance exam to keep a good options in your hand at the time of admission. 

You should be dedicated and self motivated to take admission in top colleges of engineering. There are many average student who have studied dedicately and they are studying in top colleges now. 

You can apply for top private level colleges entrance exam like VITEEE, BITSAT, Manipal, SRMJEE and Amrita as they provide good knowledge, exposure and placements.

You can also apply for your state level entrance exam to take admission in your state government colleges.

Mak sure you take admission in the college which provides good placements and faculty. 

There is a lot of competition envolve in engineering to get top colleges make sure you plan your study accordingly.

All the Best!!