You can register online with biggies/Playtex etc.... I did and I got $5 off Playtex bottle starter packs. $2 off pacifiers, huggies sent several coupons for amounts off diapers and wipes, which was made even better because babies r us are having a sale on them right now. You can also email or snail mail companies and tell them you are going to be a new mommy and want to try out different products to compare. A lot of times they will either send you more coupons or send you free samples. I got a coupon for my chicco carseat I bought. It was already on sale at babies r us for $179 plus tax and they sent me a $30 certificate towards any of their carseats. Pretty awesome.
Do you have a local department of social services. If so they will supply medicaid food stamps and wic. Food and milk for you and your baby. It actually is a wonderful program.
I wish I knew how! I'll wanna keep posted and hear advice as well.