Early in my career I contacted some of the larger Rep agencies back when they were still relevant and they were nasty as hell to me. Telling me no one wanted my kind of work and meanwhile they had 3 pages of women who glued cut paper into pictures of chickens and crap!
Haha, too funny!
I've thought about looking for a rep because the idea makes sense - I spend my time doing what I'm good at, and they have or find contacts that need it. But the internet has leveled the playing field, it's not about who you know anymore.
The standard used to be buying a mailing list (like AdBase) and mailing postcards with samples to art directors 4 times a year. A postcard is cheap, physical and marginally harder to ignore or trash than an email. If the AD liked the work, they would pin it up at their desk or file it in a drawer. I've only sent out one postcard, with weak results, but like any marketing it takes time and determination.
Like Jim, I don't pay for ads, catalogs, portfolio sites, etc. There are plenty of free portfolio sites that get way more traffic and are usually more navigable and searchable than the paid ones. Take advantage of those
Flickr is a great place to start. There's a huge community of illustrators (
including us!) and lots of meta tagging, searching and organizing tools. I've had a few clients come to me via Flickr.
I really don't see an art director taking a big catalog like Workbook off their shelf and flipping through it endlessly to find an illustrator anymore, but maybe I'm wrong.
The best return on investment is your website. It should be user- and search engine-friendly and really show off your work. If you don't know how to make your site do that, it pays to get professional help (or learn - it's a useful skill). Google will be your friend.
We're working on a post that covers a bit of this, but it's likely going to turn into a series of posts.