1. Specialize. Although many students are putting together a general set of animation skills, a professional animation portfolio should be clear in what it represents you can do. As an entry-level animator, your job will be highly specialized. If you want to be a character designer, that is what your book should contain. If you want to do backgrounds, make sure your book is one-hundred percent background work. A little of everything may mean you are a master of nothing.
2. Be eclectic. It is important to show a variety of styles. No good animators working for Nickelodeon work on one project forever. With the exception of Anime artists, animators who are not adaptable to other styles will have a difficult time finding work.
3. Turn your characters. For character designers, it is important to draw your characters in several stances. Too many front-on views does not indicate real ability. Each character should stand in multiple stances, turn their heads, use their limbs, etc..
4. Know your audience. Your work should be relevant to the company you are sending it to. If you are sending samples to Nickelodeon, be sure the work is kid friendly. You may be talented, but if your animations reflect adult themes, they won't make it very far at Nickelodeon.
5. Keep taking classes. You are never too old or too experienced to keep learning. Animators at Nickelodeon frequently take life-drawing classes to get new perspectives on how to go about their craft. Basic drawing skills are something that almost all young animators have room to improve.
Suggested readings: Cartooning for Dummies...seriously.
Suggest link: The Art of Silver - Animation portfolio for Stephen Silver, lead animator for Kim Possible, Danny Crash and the animated Clerks series...among others.
