I saw these whilst out shopping today but the stand was busy so I couldn't speak to anyone. Does anyone have experience of using them? I have pale skin with a yellow undertone tone, prone to sallowness so was particularly interested in the yellow, pink and white shades. How do you use them? (I accidentally overloaded on the pink tester and looked like I had a bad case of sunburn, although it actually made a change from 'deathly pallor')