Leiningen is the easiest way to use Clojure. With a focus on project automation and declarative configuration, it gets out of your way and lets you focus on your code.
(defproject leiningen.org "1.0.0" :description "Generate static HTML for http://leiningen.org" :dependencies [[enlive "1.0.1"] [cheshire "4.0.0"] [org.markdownj/markdownj "0.3.0-1.0.2b4"]] :main leiningen.web)
The tutorial is the best place to start. If you have Leiningen installed, you can read the tutorial by running lein help tutorial. It does not cover learning the language itself; good Clojure documentation can be found elsewhere.
Running lein help faq will get you the FAQ. Documentation for each individual task is available via lein help $TASK. You can also see the sample project.clj file containing a reference of most project settings by running lein help sample.
At the time of this writing Leiningen is the most widely-contributed-to Clojure project. We welcome potential contributors and do our best to try to make it easy to help out.
Discussion occurs primarily in the #leiningen channel on Freenode, but there is also a mailing list. To join the mailing list, email email@example.com with 'subscribe' in the Subject field, then follow the instructions in the reply you receive. The address firstname.lastname@example.org is used for posting once you've joined. Before 2016, the mailing list was hosted elsewhere; archives for older posts are separate. Issues should be reported on the GitHub issue tracker. Simpler issues appropriate for first-time contributors looking to help out are tagged "newbie".
Contributors who have had a single patch accepted may request commit rights and a free sticker on the mailing list or in IRC.