When you meet with your professor, internship supervisor or boss to ask for that recommendation, make it easy for them to say “No.” According to a new survey of law school admissions officials conducted by Kaplan, fully 87% said that they had received negative letters of recommendation for applicants. This should not happen to you! Ask only professors in whose classes you did well. When you ask, tell the potential recommender that you need enthusiastic letters to support your application. Ask the person straight out to tell you if s/he doesn’t feel s/he can do that for you. You would much rather have a professor tell you to your face that s/he doesn’t think as highly of you as you think s/he does (as painful as that may be), than to have a weak or even negative letter submitted on your behalf.
Bonus tip for underclassmen: It’s never too soon to start getting to know your professors. Speak up in class. Go to office hours and ask good questions about the class. Let your professors get to know you. It’s a big campus, with large lectures, sure, but if you take the initiative, you can build productive professional relationships with your professors.