Using drush on local machine is great. If you have problems where drush can't connect to DB of your drupal, It is probably because of the problem with PHP path so either try something like this
https://github.com/drush-ops/drush#additional-configurations-for-mamp
which advise you to put your PHP path into PATH
export PATH="/Applications/MAMP/Library/bin:/Applications/MAMP/bin/php5.3.28/bin:$PATH"
and/or use this export DRUSH_PHP=/Applications/MAMP/bin/php/php5.3.14/bin/php to add variable to make your drush run.
Seems the first one is the one that does the trick here.
p.s.
You need to have this value added permanantly in your path, otherwise it will be reset each time you load your terminal.
http://osxdaily.com/2014/08/14/add-new-path-to-path-command-line/