You might get the following error when installing with Homebrew:

==> python install

Please make the appropriate changes for your system and try again.

Fix the error by executing the following command:

sudo chmod -R go+w /Library/Python/2.7/site-packages/

An official lxml for python 3.3+ for windows has not yet been released. You may get an error while installing. Try and install an unofficial binary for lxml.