Few tips I discovered or rediscovered into "Effective Testing with RSpec 3" by @myronmarston and @undees. 
You can add conditions when tests are properly tagged. For example here run tagged jruby tests only for "Java" platform
You can choose a specific test formatter when you are running one or multiple tests
You can add conditional tag. For example to check performance.
You can add an alternate failure message
Use ".satisfy" when you have a complicated conditions
Use match with insides operator comparisons
Multiple returns on "and_return"
A good and clear example of Arrange / Act / Assert
A good example of usage of "as_stubbed_const"
You should definitely grab the book for more. Especially on custom matchers, composing matchers, test smells and RSpec configurations
