I use a powder everyday to set my foundation, reasons to powder -
* Make your foundation last longer
* Reduce shine
* Give your skin a more finished look
Also I find it easier to take powder in my bag with me to touch up my face rather than taking my foundation.
I use maybelline 24hr waterproof powder, I've always used Mac's skin finish powder but at only £6.99 for maybelline it's a bargain, and I really love the soft finish.
Do you use powder?