A few people have asked for advice on resources to help them get started with SharePoint development. Here are a few I like to suggest, add a comment if you have others.
Pluralsight On-demand Library (Subscription required)
SharePoint 2010 for ASP.NET Developers
Content was recorded for SharePoint 2010 but much of it still applies today
Inside Microsoft Windows SharePoint Services 3.0
This book is on SharePoint 2007 but I had to list it because it’s the book that helped me get started.
Inside Microsoft SharePoint 2013
The SharePoint 2013 version of the book above.
StackExchange – SharePoint
A great place to ask SharePoint questions.