I got this tidbit of help from frugalface.com

Please know that you are able to try all of our mineral makeup in person at the GOLDEN GOAT if you stop in the store.

FROM FRUGALFACE.COM

Selecting Foundation. If you don't buy a foundation you can test first, than you must be willing to exchange it, and exchange it, and exchange it again at the drugstore until you find a color that is an exact match to your face. Sometimes we are in-between the available shades and need to do our own custom color mixing. When shopping for foundation at the drugstore without testers, keep in mind that the color will appear darker in the bottle than how it will go on your skin. The Makeup Diva suggests that you bring along a favorite foundation from home to compare the colors.When testing foundation, put a swipe on your face near the jawline and don't blend it in. Let it dry, because the color will darken. Look for a color that matches your skin exactly and "disappears" into your skin. If your face and neck are two different colors, you may have to find a compromise. For example, my neck is lighter than my face. All my dark freckles make my face look darker. If I match the color at my jawline to my neck, the color looks too pale on my face. I have to go a touch darker. If you have ruddy areas on your face, make sure you match the color to your jawline. You want your foundation to cover any redness, not match it.

With your final selections, always check the color in daylight. When you decide you have found your match, always wear it over your whole face for a least a few hours to make sure the color and formula are right for you before you buy it or decide to keep it. Some foundations (especially oil-based) can change color after being on your face for a while. Make sure you do this if you have oily skin. Sometimes despite our best efforts, we can still end up with a product that turns out to be the wrong color or formula. These tips will help you learn to custom mix and adjust your own foundation colors and formulas.

Technical tips for adjusting foundation colors and formulas. Anytime you alter a foundation, either mix it in small amounts in a separate container, or mix just enough in the palm of your hand for a single use. This keeps the make-up more sanitary (if you add water you could be introducing bacteria) and if you don't like how it came out or your skin tone or the weather changes, you haven't mixed the whole bottle. You can mix larger amounts if you are only combining foundations and not adding any oil or water to them. A container, jar or bottle with a tight lid you can re-seal works well. It is also helpful to pick something with a wide opening for easy mixing and cleaning. I bought a very cheap cream-type foundation in a wide mouthed jar at Pick N' Save and washed out the foundation and I use the jar for my mixtures. Of course, you can always use any empty foundation bottle you have and wash it out.

Adjusting foundation color. I am always in-between two shades, so I buy the two foundations and mix the colors together. This is great for when the season's change. I can adjust the foundation to be lighter or darker to match my skin as it tans or fades. If your shade is too dark (or suddenly becomes too dark as your summer tan fades), but the next lightest color does not have the right "cast" to it (or you can't test it), just buy the lightest Ivory (try to avoid any with a pink or peach cast) or the next-to-the-lightest color, and mix some of your foundation with just a little bit of the light foundation at a time to get the right lightness. If you wish to keep the formula exactly the same, I advise mixing within the same brand and formula. You can mix together different brands, but at least stick to the same type of formula (oil-free, water-based, oil-based) unless you are specifically trying to alter the foundation formula. Or you may get some unexpected & unpleasant results. Mixing different brands even with the same type of formula will usually thin or thicken or alter the formula slightly in some way. It can work quite well and be very cost-effective especially to adjust an expensive foundation with a really inexpensive one. If you only need to lighten or darken the color slightly, you only need to add a little bit and it won't affect the formula much. Trial sizes can be very convenient for this purpose.

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