A portfolio is a collection of your best work, perhaps 12-20 pieces, usually in colour but with some black and white if that is your preference. Most illustrators nowadays have on-line portfolios either on their own websites or as part of a group website eg www.picturebook.com or www.childrensillustrators.com
“Portfolio” also refers to a hard copy of work that can be mailed to publishers with colour copies of artwork (never originals). According to Christine Thornton on her website, this should be "clean, professional and a standard size like 8.5-by-11 inches." When promotional samples are sent to publishers, the illustrator can mention an on-line portfolio in the hope that an art director will look at it.
"Basically, a children’s book illustration portfolio should show subjects that children enjoy and that commonly appear in children’s books so publishers know you can draw these subjects well," states Christine.She suggests that it might be a good idea to include a series of one character performing different activities with various facial expressions and body language to show the ability of keeping a character consistent over several images. Animals are another popular subject, both naturalistic and anthropomorphized.
"Include detailed settings for some of your illustrations. Remember your audience, and craft a visual world that is engaging to a child. The best illustrations are those we wish we could enter. Consider showing a variety of settings like a neighborhood, a city scene and a classroom."
For now I have made a mini portfolio using a landscape format and stab stitch. But I have spent a lot of time updating my website so that it now acts as an online portfolio, showing my illustration work alongside my writing and community art work. http://tr7431.wix.com/tracyspiers
On another website, Jennifer Farley, a designer, illustrator and design instructor based in Ireland. She writes about design and illustration on her blog at Laughing Lion Design and suggests five tips for portfolios.
1. Show Only Your Best Work
This may sound obvious, but only include your very best work. It’s better to have three or four really good pieces of work than ten pieces of rubbish. A bad piece in your portfolio is like a bad link in a chain, it will bring down the overall quality and integrity of everything else you have in there.
2. Know Your Strengths and Focus on Them
If the term “Jack of all trades, and master of none” comes to mind when people see your portfolio, then there is a problem. It may seem tempting to be able to offer ALL types of design services, or ALL types of illustration styles but that tends to make everything you do look lacklustre. Be really, really good at one or two things and stay focused on them.
3. Include the Type of Work That You Actually Want To Do
If you hate making banner ads for example, do not include them in your portfolio because you can be absolutely sure that’s what you’ll get hired to do. If you don’t have any professional experience in the area that you want to work in, create some dummy work and make up your own projects and mockups. Write your own design briefs, or find some on the web and create some high quality work for yourself.
4. Group Similar Disciplines
Group your work together logically. Organize the portfolio into categories (for example, Web Design, Logo Design, Packaging, Children’s Illustration, Medical Illustration).
5. Keep It Simple and Just Do It
For online portfolios make sure your site is easy to navigate through and completely foolproof. Provide good quality images without pixelation or distortion. Don’t agonize over your portfolio to the point where you paralyze yourself, and don’t spend to much time drooling over other people’s portfolio. Certainly you can take ideas and inspiration from others but ultimately you have to just sit down and do your own. You can tweak your portfolio along the way and as it grows you will add and remove pieces, so just do it!
Thornton, C. 2008. Demystifying the Illustrator Portfolio, available at http://www.scbwi-illinois.org/pub/PrairieWind/?p=242/accessed April 20, 2014