Migration - CRM On-premise 2011 to Online 2015

Hello,

Is there any good link or reference document to follow, while migrating from CRM on-premise 2011 to Online 2015 ?

I have searched in google and I could find some good links.

http://www.altaisystems.com/Default.aspx?tabid=3129&ID=27

http://www.powerobjects.com/2013/05/08/11-dynamics-crm-data-migration-tips/

I know that we can not directly migrate from on-premise 2011 to online 2015.

There are custom entities, plugins, processes, few web resources in existing environment with 30+ GB of database size.

What is the best way to do this ? What are the best practices to estimate such kind of task ?

Please suggest.

Thank you,

Mittal.