Something that saved me was the extensive amount of documentation-via-Stack Overflow, particularly the number of answers provided by D3's author, Mike Bostock--

Something that saved me was the extensive amount of documentation-via-Stack Overflow, particularly the number of answers provided by D3's author, Mike Bostock--often with links to working code to illustrate his answer! The amount of effort he's put in to helping people understand how to use D3 is almost as impressive as D3 itself.