Office 365 Development Setup & SharePoint PnP

Step 1 : SharePoint Online: Sign up for a free Office 365 Developer Site from your MSDN subscription

Step 2 : Login to : https://portal.office.com and use your credentials

Step 3 : The home page will be shown like the below image

4      

Step 4 : Click the SharePoint and the SharePoint Administrator page will appear as shown below. Note that the admin website link is required for some visual studio app development.

Step 5 : Create a Developer Site collection and it is highlighted as shown below

      Step 6 : Now go to https://github.com/OfficeDev/PnP and download the sample ZIP file. It contains core components and samples and need VS 2013 (I tried using VS2013)

      Step 7 : Open a sample project from the downloaded zip file

Step 8 : Now build and run the project or press F5.

Step 9 : That is it. :) ... Make sure you understand the code in the samples which will make your work easy and reduce your code dramatically. The good thing is its all CSOM and hosted in S2S (Provider hosted app model).

Reference : 

http://blogs.msdn.com/b/vesku/archive/2014/09/03/office-365-developer-patterns-and-practices-introduction-to-the-program.aspx