This article has 10 really good and helpful tips for creating a showreel. Many of them might seem obvious, but in the end all these are important.

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1: Choose your music wisely. Your choice of music should reflect your style of animation.

2: Include some lip-synching, and ensure that the entire face is alive while the character is speaking

3: Try to avoid typical characters such as hard core super heroes and robots. Create a new, unique personality with each character.

4: Keep it short. Anything from 50 seconds, too one minute 30 seconds. Humans get bored and distracted easily.

5: Create an interesting introduction and title sequence. Try to keep these similar in style, to “bookend” your showreel.

6: Include your contact details in your showreel. Name, location, phone number, website and email address is usually more than enough.

7: In your credits, give the names of the programs you utilized to create the showreel.

8: If you’d like to show off your skills in areas other than animation, find ways to creatively display your models, textures, armatures and rendering techniques

9: Your showreel is the first thing about you that a prospective employer will see. Pretend that you are introducing yourself to the employer through your showreel, and try add some of your own personality to it.

10: Give your prospective employer easy access to your reel. Phone ahead and ask how they’d prefer to view it. A small version sent as an attachment with an email? A video embedded on your site?"

Source: http://quazen.com/arts/animation/10-tips-for-creating-a-successful-animation-showreel/

This articly contains some more research on portfolio/showreels. This article also talks about applying and interviews.

"In the computer animation industry we have what is called a demo reel. A demo reel is a short video showing off your talents and skills. Think of it as a resume. To give an employer an idea whether or not you are qualified for the job, they need to know what your skills are and if you fit what they’re looking for. Rather than reading your qualifications and you telling them what you are capable of, they get to see exactly what it is you can do.
If you went to a good school, they more than likely helped you with your demo reel. But for those of you who didn’t make one here are a few things you want to be aware of.

Length

You don’t want to put everything you’ve ever done on your demo reel. Keep it short and to the point. You also don’t want to make it too short either. A two to three cramped reel will do fine.

Good Work

This goes without saying but only put your best work on your reel. Your first animation tests that you were so proud of won’t cut it. Unless you nailed it right off the bat, which is highly unlikely, you don’t want to put the first thing you ever racy on your reel. You’ll be known for the worst piece on your reel. The worst thing on there will stand out and they will judge your entire reel based on it. So do not put anything that you don’t think is top notch on there, period.

Repeats

If they want to see something again, they can simply rewind the tape. Don’t put the same thing on your reel twice because you idea it was great. This will also show that you don’t have enough material if you have to put the same things multiple times. If you don’t have enough obliging material, don’t develop a demo reel until you do.

Creativity

People are tired of looking at spaceships and fancy robots. Too many people put this stuff on their reels and after looking at it a thousand times it gets worn. Putting something on your reel that hasn’t been seen before will go along was towards making you stand out from the rest.

Music

It’s really simple don’t put any on there. They want to see your animation skills not whether or not you can gather the soundtrack. Many will listen to you demo muted anyway so you don’t need to put any on there. If your piece absolutely needs music, do sure it fits and check the levels so you don’t kill anyone’s eardrums

Specify

You want to tell exactly what you did on the reel. For the most part if you’re just starting out you most likely did everything on the reel but after you have been working and you simply want to move to another job you may have work that you collaborated on. You don’t want to claim work that you didn’t do. Simply save modeling, or animation only over the piece if that’s what you did.

Label everything

Obviously you want them to know that you are the one who submitted the reel. Put your contact information on the tape and at the beginning and end or the reel as well.

You also want to specify what position you’re applying for so it gets to the right department

Tailor your reel to fit the position you want as well. You may want to be a character animator but if you have nice lighting or textures they may notice that instead and choose you for that job.

Minor tidbits

You want to make sure that every tape you send works. This may be insensible but you have to watch your finished reels. If it’s a bad tape with a bunch of static or it’s poorly edited you don’t want to send it to anyone. If you go through the entire reel and there are not errors, create sure you rewind it to the beginning. You don’t want your potential employer to have to rewind your reel, because they most likely won’t bother, they’ll just chuck it out.

Get a novel tape. They’re not that expensive. You don’t want your home movies in the middle of your demo reel. Also recording over other footage will lessen the quality.

Getting the job

With your demo reel all ready to go you’ll want to actually originate applying to jobs. You’ll want to go about this like any other job. Take your resume and reel and apply. Do an interview and pray for the best.

You may already have places you’re interested in working at, if not you’ll want to do a search. Find a place that will fit your interests. Don’t limit yourself to applying to the big name studios. You may find a smaller studio will fit you better. 3D animation isn’t limited to films either you may want to work in the video game industry or commercials too. Purchase a look at their other work and see if it’s something you want to do.

Like any job you want to be well dressed and on time for your interview. Be prepared. You’ll want to know exactly what you are capable of and be able to clarify it to your potential employer. Know what’s on your demo reel. They may ask you how something was done and if you can’t snort them anything about it you’ll look bad.

Remain calm. Relax and retort any questions to the best of your ability. When the interviewer is done, they’ll most likely want to know if you have any questions you would like to ask them. Fabricate sure you have something to say; it helps to learn about the company.

A sad truth in this industry, who you know can often land you a job, but it can also hurt you. The animation industry is relatively small. You’d be surprised who knows each other. This goes with any job but don’t talk bad about a previous employer. Your previous employer could be a relative of the one you’re interviewing with. On the opposite coin if you’re in good standing with a previous employer that can be a foot in the door of a future job.

A good way to make contacts is to attend events. Conventions or festivals will put you in direct contact with people in the industry. You can also leave your demo reel with companies at these events.

This industry is highly competitive and if you aren’t the best you can possibly be then you won’t make it. Make sure you go to the right school or if you learn on your own that you stay focused. Try to get the best education you can. Effect together a strong demo reel. This is often the deciding factor when getting a job. Be distinct to attend events and get involved in the industry. Siggraph is the premiere event for all things computer graphic related. You will pick up to see what the industry is all about and you will build strong relationships for the future."

Source: http://customer-support-software.org/knowledge-base-software/how-to-get-a-job-in-computer-animation/

This blog will be updated with my progress while researching how to work as a Freelancer in the animation industry.