If you sign with your baby, consider teaching him or her "please" (flat open hand circling on the chest) instead of "more" (all fingers tapping in a bunch).
Practically, they mean the same thing to your baby ("I want!") but for parental sensibilities (I like to be asked!), and training to build on further down the road (you keep saying the same thing, even after they can talk), I've found "please" to be infinitely better.
I may have won the prize for the most parentheses this round. ;o)
Have a blessed day!