I'd just like to speak briefly about an easy and cost effective way to test your paints.
Traditionally, I would test my paint by spraying some on an unused action base, paper, or leftover runner. Since then, I've found that a better way to go about it is to test on some disposable white plastic spoons.
One can usually find 100 count packs of these disposable utensils at the local grocer for less than $5. They provide a nice consistent colour and surface to test upon. (Note - Make sure your spoon's surface is clean before painting, sometimes there's dust and other material floating around in the shipping container) If you're interested in establishing a collection, you can write the paint's information on the stem for later reference. You can pull them out at a later date to compare and contrast paints you've already tested when planning a colour scheme.
In addition, it also lets you practice your painting methodology and note any issues with the paint (e.g. runny or doesn't dry smoothly). You can also test various layering combinations (such as gray v. white primer base) or how a top coat will look.