The purpose of a primer is to provide a smooth, moisturised surface to apply make up on to.
One of the primers I use is the Guerlain Meteorites Primer (£42). I have actually worked for Guerlain and this has proved very popular amongst customers. I LOVE this primer as it is so light and silky on the skin. You only need to apply a little bit, a little goes a long way as it leaves the skin feeling so radiant. Furthermore, the product itself looks and smells gorgeous.
The second primer I use is the Fix and Perfect primer by Rimmel (£6). This has a slightly thicker texture compared with the Guerlain Primer, and again you only need to use the smallest amount. I would definitely recommend this as one of the better drug store primers. However, I would say avoid using a moisturiser underneath this, especially if you have oily skin.
What primers would you recommend?