I agree with others who recommend getting good shoes. The first time I tried to go from SPDs to flats, I got decent pedals and tried a bunch of shoes that I already had, none of which worked very well at all. Quickly went back to SPDs. A year later I tried again with 5-10 Free Riders. Big difference. I'll never ride SPDs again.
Also, if you have big feet, I'd get something bigger than Chesters. I used some Crank Brother Stamps for awhile (big pedals), then got some Chesters for a commuter bike. No comparison, the Stamps give me way more confidence than Chesters (which are fine for many, especially if you have small-to medium sized feet).