If you do not have a good academic performance previously, then there is nothing that you can do to change it. So there is no point in crying over that. Placement at college campuses is itself dependent on so many variables, including luck, that it is difficult to predict who will be placed where. People with stellar grades and superb academics throughout have struggled to land top jobs while average grade students have bagged dream roles in big companies such as Google and Apple.
Now there are certain things which are in your hand which can certainly help improve your chances during placements.
If you do all the above things you will definitely bolster your chances of getting selected at those companies. But remember one thing, you should aim for a job profile which interests and suits you over an uninteresting job at a top company.