Here are some tips I've found myself or from friends:
Angel Food Ministries
https://www.angelfoodministries.com/
This organization gathers groceries and puts together boxes for purchase. There are no income requirements and it is for anyone who needs to cut costs and still provide good food for their families. It's a great idea and a great way to save money on items you'd pay more for at the store. There are locations everywhere.
Yard Sales or Thrift stores
Many children items can be bought for little and look almost new since children grow out of them so quickly. I know that some Thrift stores in my area offer dollar days where you can fill a paper grocery bag for a dollar. GREAT DEAL and SAVINGS!!! :)
Diapers:
The best brand I have found are the Walmart Brand Parent's Choice (I think that's what they are called). They are better than the more expensive name brands and cost much less. You might also find them at Sams Club and buy in bulk for an even bigger discount. Best wipes are Target Brand, but I also use my grocer's brand and Walmart Brand as well. Don't buy name brand when the off brands are just as good if not better.
Coupons:
Find them, cut them, use them....BUT don't get caught up in using coupons on items you really don't need. I look at the coupons and cut what I know I'll use because I use it all the time or I know I'll need it. I use the coupons only if the generic brand is more expensive than the name brand with the coupon, otherwise I go with the generic brand. Also look for sales at your grocery store and try to match them with coupons. BOGO sales can be great deals when you also have some coupons too! :)
I know I didn't give you an amount, but that is different for everyone, so that's hard to make a judgement. I hope that these tips have helped. Good luck! This economy is scary and we should be joining together to help each other live smarter. :)