Regardless of your academic field, the ability to communicate ideas and thoughts in a coherent, clear, engaging manner is of the utmost importance. Most classes involve some degree of public speaking, whether you are participating in a class discussion, presenting a paper at a conference or lecture, or competing in an in-class debate.
Nearly every college or university has a communications department which offers courses in public speaking. Some universities even require that all students graduate with a public speaking course. Check the requirements of your university, and seriously consider taking one if it is not compulsory for graduation. The best way to improve as a public speaker is to practice, and a public speaking course will give you plenty.
Breathe regularly and evenly; this will calm your nerves, project your voice and keep your from speaking too quickly. Speak to the back row of the room in order for your voice to be adequately heard. Familiarize yourself thoroughly with the given material; public speaking will highlight gaps in your knowledge and can make you look unprepared. Engage the audience with eye contact.