I wish I could say that we have a rubric or something somewhat systematic that guides my buying decisions... but I have no such process. For now, these are the things that I consider:
1.) If I feel like an Importer does an especially good job with their partner producing groups, I'm much more likely to keep buying from them. I've stuck with some Importers as their products have shifted just because I trust how they prioritize the producers. Working with coops in different cultures is really difficult and I want to support the people who keep with it even when it must be extremely frustrating.
2.) The products need to seem like they will sell in the mid-west. ;)
3.) Even though all of the prices are fair in Fair Trade, that doesn't mean that they are all affordable for us. I have to feel like people will actually be able to purchase an item to bring it into the store.
4.) I try to have a variety of products and a good selection within each type. Sometimes this means that I have quite a bit of backstock which isn't the best business practice, but often Importers run out of product. I want to have the goods available to customers that I think are the best. Usually it all works out. :)
5.) We have wonderful artisans here in Lindsborg. I've never intentionally carried a product that they specialize in. We actually have a coffee roaster in Lindsborg as well so I tuck a little coffee in a back corner of the store for the people who have specifically asked to be able to buy Equal Exchange. There is so much Fair Trade available that there is no reason for me to overlap with my good neighbors.
That's about it! I'll keep evolving and learning as I go, but for now these are the things that guide me along... simple! ;)