Templates. Templates provide a means to centralize project configuration in a single file. Common setup chores like installing gems, plugins, JavaScript libraries, adding initializers, or writing custom rake tasks can be automated. Use rails app -m mytemplate at creation time or apply the template to an existing project. Browsing templates on github is also a nice way to see what tools and techniques other developers are using.

Use nested model forms. I have found creating and updating nested models to be problematic. My suspicion is that nested model forms will work better in the next major version of Rails. Using the feature now maximizes forward-compatibility.

Use seed data. rake db:seed and rake db:setup are new tasks to manage real application data while the application code is being developed. Understand the difference between seed data and test fixture data and explain it to your team member who may be creating the seed data if that person is not you.