Work at Home

A lot depends on the kind of work you're qualified to do - is it something that lends itself to working from home?
You are absolutely right - you don't want to give out credit card information or pay for the privilege of working at home - with one possible exception. Some telecommuting job and freelancer sites - for example, Guru.com and eLance.com - offer more features and more positions if you register with them and pay a membership fee. That's how they make their money. Although sometimes you can get a free basic membership, you'll find that the information you can access and the projects you are allowed to bid on are severely restricted unless you opt-in for a paid membership.
A work at home job site like TJobs.com requires you to pay a small annual membership fee - the last I checked about 10 or fifteen bucks for a membership password good for one year - to access their job postings. Some of the virtual assistant websites and other job registration sites also work that way. So while you might consider paying a registration or membership fee for a site that offers job postings in the area you're interested in, you never want to pay an "employer" directly for a job - those are just scams.