I find the best (and least frustrating) path is to start with Allow from All
, then, when you know it will work that way, scale it back to the more secure Allow from 127.0.0.1
or Allow from ::1
(localhost).
As long as your firewall is configured properly, Allow from all
shouldn't cause any problems, but it is better to only allow from localhost if you don't need other computers to be able to access your site.
Don't forget to restart Apache whenever you make changes to httpd.conf. They will not take effect until the next start.
Hopefully this is enough to get you started, there is lots of documentation available online.