This popular approach works for many people. Follow every link on this site, farm the pre-defined searches, locate the support available via the DMOZ Entries, shop for what you need, and THEN get started.
I like this idea better. Just don't let the planning and shopping get in the way of getting started.
What kinds of foods are helpful to keep on hand? Here are a few suggestions that support a vegetarian approach to "No Flour No Sugar":
Planning & Shopping can stack the odds in your favor. Once you're ready, you'll have to identify some moment in time to make the shift. At that point, you'll have to go "Cold Turkey." But, if you want, you could keep baselines and initiate a detox process. (Recommended.)