Shopping for luxury goods like Chanel or Louis Vuitton in an EU country is more exciting as you can get a tax refund if you are not a resident. Here's a guide on how to get a tax refund when shopping in places like France or Italy. Note that there are different thresholds on how much to spend in each country. The limit in France for 2013 is 175 Euros.
At the Boutique
A minimum amount is required to be spent prior to the retailer completing the forms. Talk to your sales associate and let them know that you want to participate in the refund. The refund will occur AFTER all the documentation is prepared, then stamped at the airport and mailed back to the retailer.
At the Airport
While at the airport, get there early to get your documents stamped as typically there are long lines and this step is performed prior to check-in. Ensure you leave ample time for check-in. Once stamped, the documents are mailed back to the retailer so your refund can be processed. The mail out will likely happen when you are in the destination country unless you find a way to mail back at the airport.
For retailers that use a service such as Global Blue or Premier Tax Free the refund can be done at the airport. A large fee is usually taken for it to be done immediately. They have locations in the airport.
The refund will depend on the EU country you are in but Paris is typically 10.5% - 12% depending on the form of payment. Check out Rick Steves guide on the percentage refund by country and the steps to take, it's very comprehensive.