Any new member who uses the free signup is established as s2Level-0 You can set all your pages except the "Public Pages" to require Level-1 or higher and you (admin) can manually go in and set users to any level you want which will give them access to only what you want.
The Level-0 members will only be able to access the public pages
RGIEF: It sounds as if you want to prevent selected individuals like competitors (even competitors who PAY to be Level-1 or higher) from gaining access to protected content. Is that right? If so, I'm not convinced man-o-media's solution would suffice.
You are sort of correct... There was no indication that paying was going to be involved but if there is a paying factor then it would be best to have any paid memberships start at level-2.
That way, you could manually elevate "approve" users to level-1 which would gain them access to the page or pages needed for paying for higher/alternative access. Anyone with only level-0 access would not be able to see those pages.