The Google sandbox is a concept that Google filters results Google knows what are the big money keywords - from adsense bids etc They hold back webpages for a time The primary keywords are the ones the clients demand in their sleep I want "New York Hotels" for example Google knows this - it holds back these primary keywords for some time Just do your work , be diligent One morning with effort ( if you have chosen your battles) you will wake up and there you are with your site or sites ranking in those dominant areas in serps
search you website URL in google (ex. www.example.com) and if you don't get your website in SERP then consider that it moved to sandbox
The only way out af sandbox is twice as hard work, patience and good content on site. I made a site that is almost out of sandbox after 5 month.