I have extremely oily skin and work 12 hour shifts, which means my face is almost guaranteed to look cakey. I've found that less is more... more foundation and more powder means more opportunity for the oil to soak it up and look thick and awful. The only thing I've found that works for me is to use a thin gel-type moisturizer (currently I use Neutrogena Hydro Boost gel) and layer two primers--right now I'm using Bare Minerals Prime Time (it's ok, not sure I'll buy this one again) and a layer of Trader Joe's Nourishing Antioxidant serum over it (this stuff has the consistency and ingredients of a primer; I hardly consider it a serum). Then I use a thin application of long-wearing oil-free foundation with clean fingers and concentrate it mostly on my T-Zone and blend it out. Then I use a small brush (like a travel blush brush, not a huge fluffy powder brush) to set only my T-zone and concealer. I find that if I leave the rest of my foundation un-powdered, it stays looking more natural. The extra layers of primer help slow the breakthrough of oil, and when I do start to look shiny I just blot but don't add more powder. I usually look pretty great until about hour 11 or 12. Also, ymmv but I've tried several higher-end foundations and powders but found that the chalkier consistency of the lower-end products works better for oil control. I recently stopped using Tarte Amazonian Clay and switched to Revlon Colorstay for oily skin and its accompanying pressed powder and am quite pleased with the results.