Hi, Google says that a healthy site should have more do-follow than no-follow (I use 70-30), you can use relatively new web2.0 (less than 15 days) for no-follow, it does not give juice so PR does not matter. Content of the web2.0 wouldn't matter much, but I would suggest creating a post related to your niche (parent niche) just so that the link would look natural. Scrap 5-7 blog (no review or ad posts) from another web2.0 and use it as rest of the content. Good luck.