Consider for a moment how your phone is currently being answered. Professional courtesy is quite often not the standard for many college students. An abrupt "Yeah!" could be listed among the more courteous greetings. The more outrageous remarks will often buy you a major black mark in the professionalism category—even if it was your roommate answering your phone and acting crazy. A simple "This is ____" is always a pleasant change for a college student call. Make the change today, before the next (or first) employer phone call. If you have a landline, you should also encourage your roommate to do the same.
Keep it simple, concise and to the point. Callers won’t need your life story, and won’t want to wait around for a 2-minute greeting to end just so they can leave a message. Don’t hide the details, tell them where you will be, when you will be there, or when you won’t be there, and how to get in touch.

Many busy businesses utilize auto attendant greetings to make a great first impression, however, if your business relies on the personal touch of a live receptionist, it is important to have a plan in place when that position is unstaffed. Make sure your voicemail greeting contains the useful information that your receptionist would normally provide. This could include: location & directions, office hours, website URL, or social media info, as well as any pertinent company information.
A separate greeting can be created for after hours, and typically includes additional options for customers, or at minimum, informs them that your office is closed. In these greetings, it’s beneficial to inform your caller of your regular business hours, as well as provide them with a link for technical support, or additional contact method (if applicable).