When defining your customers, you can't avoid generalizing. For generalizing, you need some critera and good sources of information. One of the sources i've always liked is the cia factbook, a site which covers a lot if not countries in the world, in various aspects.
Then there is the government cencus office of the country your customers live in. Some examples are the Dutch census, the European census, the Brazillian census, the UK census .
I'm sure you can find the rest in Google (search for "National Statistical Organizations (NSOs)" , or wikipedia
It's also good to take a look at the chamber of commerce of the country, as they are there to facilitate businesses.
In these sources of information you can find many generic data that may help you greate a "normalized user" which will show the difference between your customers and the average user.
The last group of statistics that may be of interest are the internet statistis gathereres. Some interesting sites here are www.geodemographics.org.uk/, www.emarketer.com , http://www.pewinternet.org/ and others, although you'll have to pay for more information, or read through the articles, collecting the data you'll need.