Use vim-ruby-refactoring to quickly perform common refactorings. My 2 favorites:
Post-conditionals
unless current_user
"Hello guest!"
end
:RConvertPostConditional or <leader>rcpc
"Hello guest!" unless current_user
Local variables
raise if current > values.to_a.mean * 2
:RExtractLocalVariable or <leader>relv, and then name your variable
double_the_mean = values.to_a.mean * 2
raise if current > double_the_mean
See more examples here.