Number 1 and most important: Get to know your stores coupon policies. coupondivas.com has a great individual store breakdown.
For example, I mainly shop and Shop Rite, they have two different coupon policies as a business but each store can choose which one they want. They have a 4 of the same coupon her person per day at mine. Which is really dumb, TLC's show has really ruined it for others.
My store will also double UP to .99. Also they will only double up to the cost of the item, they don't give money back, another way Extreme Couponing has ruined everything. Still not complaining because free is free. If you have a box of cereal for $2 and a .75 cents coupon they will double it to a $1.50 cent coupon making it .50 cents.
Check the sale flyers in your paper and check out sites like CouponDivas to check out the ads, sales and what coupons you can use. Also remember stores like Target have Target specific coupon which you can combine with manufacturer coupons. Combine with sales if at all possible to have max savings. For example if Caress body wash is normally $3.00 and they have it on sale for $2.50, and Caress has a .75 cent coupon and Target has a $1 dollar coupon - combine all of those savings and get the item for .75 cents.
Only buy items when they are free or close to free - stock up when you can that way you do not run out of that item and have to pay full price when needed.
There are many more tips but this is what I have for now. Check back often for more steals, deals and tips!