I tried to find scholarships that were about something I was interested in or something I was already doing in class. Also, once I had a winning story for the writing contests/scholarships, I submitted the same entry to several. Since 2004, I have won over 15 worth nearly $50,000.
If you like to write, tackle the scholarships that require a high word count. They have fewer applicants than those that require little work. That gives you better odds of winning the scholarship.
I always have someone look at my work before I submit it because I am too attached and make simple mistakes, which is one of the top reasons your application will be rejected. Edit, edit, edit!
I ended getting about 4 or 5 in the end, but still not enough to cover my tuition. Most of them were after Graduation as they announced who gets the ones through the school on Graduation day. Sometimes you can get them through FAFSA and the school itself (some schools use your FAFSA in order to award those in need with scholarships- check with your college before taking my word on it though).