I like MoJoSavings and Freebies4Mom. I print a lot of coupons off of coupons.com as well. Depending on where you shop, you might be able to load your coupons directly on to you shopper's card. I know Kroger has that ability. I love it! The only thing is that the coupons on there don't double, but a lot of times you can use the coupon that you loaded onto your card as well as a paper coupon.
Also, coupons.com goes by your zip code. If you enter a zip code for a larger city, you sometimes get better coupons.
I see those extreme couponers and they make it look so easy. It's not. They do a LOT of research to find out which store has the best price. I tried it awhile back. I was saving money, but I also found that I was spending a lot of time and gas driving all around to different stores. If I have a coupon for something I like, I get it. I think a lot of the times those extreme couponers are buying things they don't really need. They're just buying it because they have a coupon.
Another tip is to look at the price per ounce or the price per unit. In my personal experience, buying the store brand is generally cheaper than buying something with a coupon.