I am a SAHM mom of 5 boys ages 13 years to 23 months old.
Some things we do are put in a garden and I can and freeze fruits and veggies in season when they are plentiful and cheap.
Also stock up on sale items, such as meat and boxed/canned goods from the grocery store and store them at home so when I need something I have it here and don't need to run out to get it at full price.
I also garage sale for things, you would be amazed at what you can find that is almost new for a fraction of the retail price. Kids clothes, household items, it really helps stretch the budget.
I also shop all year long for gifts, if I see something on clearance I pick it up and stash it away until someones birthday or christmas, if you plan ahead you can still give nice gifts for not alot of money.
I also cook as much as I can from scratch, such as quick breads, and I have even recently found a way to make homemade yogurt in my crock pot! This is great as my kids eat lots of smoothies.
I think the trick is in advance planning. Also we are debt free, I think if we had much credit card debt it would be a lot more difficult. We typically don't buy something unless we have the cash for it. Occasionally we make an exception, but will have the credit card paid off completely in a month or two.
I hope this was helpful, and if you would like more details about anything that we do I love to talk about it!