I found Elastic Search one of the hardest things I've had to learn, I hadn't used Lucene before and I found the documentation to be quite hard to follow.
These are the things that I wish I'd known before I started learning it:
Configuration and setup
I configured ELS to run on 3 VM' using Centos, Mint and Ubuntu. Centos was by far the best choice of the three.
I followed this guide to help me set it up (it worked fine on all three distros)
Index and types
One Index can contain many types, it's by using types that you can achieve a good degree of separation of data that belongs within the same index.
PHP
I use PHP as a front end and used this wrapper to integrate my ELS installation into my scripts.
Other resources
The presentation in the other answer to your question is really good, go through it and learn the DSL Query syntax, once setup this is where the real power of ELS comes into its own.
