Edit (sudo) /etc/apache2/users/[your-username].conf:

1. Add Doc­u­men­t­Root "/Users/[your-username]/Sites/" at the top of the file;
2. Add Fol­lowSym­Links to the Options;
3. Change Al­lowOver­ride None to Al­lowOver­ride All;
4. Change Deny from All to Allow from All.

Original:

<Directory "/Users/[your-username]/Sites/">
    Options Indexes MultiViews
    AllowOverride None
    Order allow,deny
    Deny from All
</Directory>

New:

DocumentRoot "/Users/[your-username]/Sites/"
<Directory "/Users/[your-username]/Sites/">
   Options Indexes MultiViews FollowSymLinks
   AllowOverride All
   Order allow,deny
   Allow from All
</Directory>

Restart Apache: sudo apachectl graceful