/bin/setup

It's quite nice when you take over a project and you have simple instructions in the README. For example, you could specify the manual steps and then tell the developer to run ./bin/setup

This is a pretty standard setup bash script:

#!/bin/bash

cp .ruby-version.sample .ruby-version
cd .
gem install bundler --no-ri --no-rdoc
git submodule init; git submodule update --init
bundle
mysql.server start
bundle exec rake db:create
bundle exec rake db:setup