There are some good tutorials available.
There is a shorter version of the official tutorial with just highlights
There are also “Sage quick reference documents” for several subjects on the Sage Wiki. These are useful cheat sheets with frequently used commands, organized by subject.
You can also look through relevant documentation.
There is the page for all of the official Sage documentation.
The Python Documentation. Note that Sage uses Python 2.x as of the time this page was written.
There a useful Q & A site:
Relevant Google Groups mailing lists:
And an introductory book:
For a list of interesting examples, you can pull down an officially curated set of example files by going to the “new file” page and pasting in this address:
https://github.com/sagemath/cloud-examples.git
This will create a directory in your project called cloud-examples
which contains
lots of interesting things.