I tried
this search[
^]. This should give you plenty of ideas. Just be aware that online sites tend not to pay too well - you are up against so much competition who can severely undercut you because they are working out of their bedrooms.
A better way to get clients is to network yourself. By this, I mean that you should attend business meetings; your local chamber of commerce will be a good place to find out about these meetings. When you have some client history in your portfolio, you could also try to get in on bid-tenders.