How to become a great couponer?

I recently watch " EXTREME COUPONING" on TLC. I have now put together a coupon binder, I have read several blogspots for the lingo, matchup, and budgeting. What I dont understand is how they have so many inserts with purchasing them or dumpster diving? How do they get their balance so low even with meats and fruits at checkout? does anyone have any suggestions to become an extreme couponer