I would too suggest a portfolio. Keep it professional. That often means no fanart, no gore, no student studies (artschool-looking stuff). But that depends what your product is. This will probably help you "get out there".
Got the same problem. Well this site here is already not bad. Conventions and forums are not bad. Look for ways to get flyers and cards around. Besides your own website, a facebook account with gallery and news can also boost you a bit.
But most of all, try to get in contact with people. Look for magazines in the particular sector you're active in. Try to get the names of people, so you know them. Don't just talk with secretaries on the phone. Make sure people know your stuff and know YOU. It's hard and time-consuming but that's the way. Never give up on it and don't forget that luck also plays a role sometimes.