Sandbox is a google update which happens usually with the new websites. It means that google has less trust on your new website. The best way is to give social signals. Social signals provide immense trust in the eyes of google. The best social signal to give is google plus and after that twitter. Once you start giving backlinks and social signals soon you will get out of the sandbox effect.
One of my friend works with
Kimik Studios - Social Media Agency In Delhi they got affected by sandbox and with these steps they came out of it.
Cheers
Would love to answer more doubts.