When you're writing a portfolio, you need to first consider your audience, as this will help you gauge which of the material/experiences you have are most significant.
By organising your work this way you will be making sure to keep your reader interested from the start, with only the most relevant work being mentioned (though if you don't have much experience you may want to relax this rule a bit).
Be aware, this is not a CV (but if you want to write a CV, check out this other Blurtit page - //employment.blurtit.com/98052/how-to-add-experience-in-a-cv-)
Writing your portfolio
Your work is often creative in a portfolio, so you want to keep it simple, but include the date you completed the work, the company/reason you made it and link to or have an example of the piece. A great way to do this is use a pre-existing portfolio writer online, some good examples are:
clippings.me - for writers or journalists as it has specific writing portfolios.
about.me - which works as an online portfolio and CV, it is free and easy to use with simple categories to fill in.
Because your work may be creative make sure you include lots of images/soundbites/video's of it, because presentation is key and by having multimedia segments on your page, you will allow people to view the work without having to go searching themselves.
The secret to an amazing portfolio
Remember the most important part of a portfolio is that you update it regularly. This is a continual project and will pay off in the long run if you aren't having to do everything last minute and can keep reorganising your work. A portfolio is a great way to exhibit not only your work but also a bit of personality, just make sure to keep it professional.
This is a really great video by a graphic designer explaining how her portfolio works:
If you are interested in a design portfolio this video gives a very current view of what designers are looking for and these rules can be applied to photography, architecture and many more: