welcome.

as a long term webmaster, i can tell you that a lot of people who would be happy to receive free writing will be equally happy to remove your link from their sites.

what's more, the people with serious traffic aren't that likely to want to send their traffic away. they'd prefer to spend cash on writers and keep their traffic. i do a lot of work as a copywriter and site reviewer.

whether you decide to charge for your services or to do the writing/traffic trade, i think a couple samples would help more webmasters to take you seriously.

good luck to you!