custom enterprise solution with project server 2010

Hi ,

I begin to develop custom enterprise solution with project server 2010 (financial module, CRM, and project management) , and i look for some one how can give me advice about the solution's structureshould I use and the best practices. Often i use VS 2012 and info path(to create list in pwa site collection) and i hope using separation layer in structure of my solution.

Sorry for the newbie question.

Thanks and best Regards,