I use RSpec in all my projects. It’s really hard to overemphasize how helpful it is and how much easier becomes your life if you have good specs coverage. But its outstanding flexibility enables many ways to make your specs awful: horribly slow, over-bloated, even non-readable sometimes. I do not want to teach you BDD and RSpec here, but instead I will give you some ideas how to improve your specs quality and increase efficiency of your BDD workflow.
RSpec has great feature — mock objects (mocks). In a few words: mock object imitates behavior of the object, which used by the tested methods. And simple example immediately:
it 'should generate correct link to user profile in user_link' do
@user = mock('User')
@user.stub!(:preferred_name, 'Dmytro S.')
@user.stub!(:full_name, 'Dmytro Shteflyuk')
user_link(@user).should == link_to('Dmytro S.', user_url(:id => 10), :title => 'Dmytro Shteflyuk')