Here is my guide to getting a perfect base:
You must start with clean, smooth skin. I suggest cleansing thoroughly with an oil like Nude Skincare Cleansing Facial Oil http://www.nudeskincare.com/ to remove all traces of makeup and dirt. Then smooth your skin's texture and brighten at the same time with Liz Earle's Brightening Treatment http://www.lizearle.com/ which is a quick face mask that you remove with a hot muslin cloth that acts like a mild exfoliant and revives dull complexions. Next apply a non greasy moisturiser suited to your skin type - for aging and or dry skin I like Alpha Derma CE by Janson Beckett http://www.janson-beckett.com/ as it has tightening properties and leaves skin glowing. If you have oily/combination skin try Oil Control Mattifier by Murad http://www.murad.com/ which is honestly the only oil control lotion I have ever found that actually does the job (this is also good during the Summer months or in humid climates to control shine)!
Now you've prepped your complexion you can massage in a primer if you like to use them - my favorites are Face Forward Primers (both Age Response and Acne Response Formulas) by http://www.alisonraffaele.com/ . Let the primer settle for a minute and then take your preferred base, I use Hourglass Veil Fluid Makeup http://www.hourglasscosmetics.com/ on all my clients, and put a little on the back of your hand. Using a wedge sponge (I prefer sponges to brushes as I think brushes just leave a mask like layer on top of the skin and it looks heavy and unnatural) dip into the foundation and blend well from the inner areas of your face out towards the edges. You usually need more foundation in the center of your face and less on the outer, as the skin is usually finer here. Blend thoroughly, making sure there are no tide marks under your chin and you have blended around the nose, an area people don't check and believe me I've seen it looking extremely crusty before - not a good look! Taking a good concealer especially formulated for the delicate skin under the eyes (Age Repairing Brightener by http://www.jouer.com/ is ideal) dot it straight from the tube or using a small brush apply it from the inner corners to the outer corners, not forgetting the little crease at the edge of the eye and gently blend with your ring finger. If you are using the right concealer it won't cake or accentuate lines and will make you look brighter and younger. Using a smaller brush conceal any pimples by dotting concealer on top and patting it in, being careful not to rub it off - Acne Treatment Concealer by http://www.murad.com/ is great for this. If you use cream blusher now is the time to add it to the apples of your cheeks and yes you guessed it blend, blend, blend! Dust a very fine layer of powder over your your whole face with a big fluffy brush to set your makeup, help it last and also give it an airbrushed quality - Hourglass Invisible Veil Powder is perfect as is Transparent Finish Powder by Alison Raffaele.
You now should look flawless and have a great canvas for the rest of your makeup!