There’s no better place to start than Steve Yegge’s post, where he dicusses the Jeff Bezos memo that kicked off the service architecture revolution at Amazon:
The RESTful cookbook is a your next stop – an easy to digest of many of the key topics:
Then you should read this classic worked example – ‘How to GET a Cup of Coffee’:
(If you read the comments section of the article, you’ll get a useful taste of the kind of design discussions that come up in the field)
The REST API Design Handbook is a good, quick read, once you’re starting to get more confidence:
It’s a little dated now, but the RESTful Web Services Cookbook is a great resource once you start needing deeper coverage on topics such as asynchronous calls and versioning:
Lastly, if you want to see a standard for REST API design published by an organisation that’s got some serious experience, check out this public document from Zalando:
It is long, but you’ll find yourself agreeing with most of it.