Personally, I wouldn't take on a "revenue share" writing job. She could do the same work and get all the rev earnings by simply posting on her own to rev share sites, such as hubpages.
When it comes to online writing work, I follow a few rules. 1) Never provide a free sample, especially if they assign the topic. I am more than happy to provide clips of my previously published work. When I first started freelancing, I had a freebie webpage with several samples on it that I would refer potential clients. 2) Get an EIN from the IRS, and use this instead of your SSN. 3)Piggy backing off of #2, private clients usually don't need your SSN. A few will insist if they end up paying you more than $600 during the fiscal year, but most won't. Online content companies will want it, though.
If she really wants to break in to the business, feel free to send me a message. I can send a few tips and possibly some leads to jobs I know are legit within her preferred writing niche!