Nobody knows how to get out of the Sandbox. Well, except for a few people at Google. 3 months is a very short time to be in the sandbox, no matter what industry your site is in. Most people believe there are certain triggers that put your site in the sandbox and certain triggers that eventually release it. What nobody seems to know is exactly what those triggers are. Certainly content and links are part of it, but there are probably 50, heck maybe 100 other factors.