Virtual Domains & Apache2

I'm new to configuring Apache and I had some trouble so I thought I'd
share.

I was getting a [warn] message with "has no virtualhosts".

First of all I ensured that my default <virtualhost *> was loaded first
by using a numbering scheme in ./sites-available.

eg. 001-default.conf
002-firstdomain.com.conf
003-seconddomain.com.conf
etc

What I originally did was copy the original "default" file from Apache2,
but it has at the very top the NameVirtualHost entry.

I just had to remove that line from all files except for my first
one...ie..default.