Baby sign is lauded as a means to allowing your small babies communicated before they can vocalize well, and as a way to prep children for excellent word mastery later on. With both of my kids, we have used baby sign as a way to teach words.
When my oldest was a baby, we had many words we used (loud; play; cat, etc.), but with my second, we stuck to the ones we used the most: milk, more, all done, thank you, sleep.
As fate would have it, it seems baby sign did work very well for my daughter, as she is by far the most eloquent 5 year old I’ve come across (even at 2.5 saying things like “what is that infernal racket?!’) For my son, it was absolutely helpful when he was very frustrated pre-speech with his desire to communicate. However, once he could talk, he has almost entirely abandoned any signs, aside from the occasional ‘milk’ or ‘all done’.
To learn the signs, we purchased a set of baby sign flashcards from our local bookstore. From there, we selected out a few at a time, and tried to use them as much as we could remember. Once those were second-nature, we added to it.
my daughter showing her continued – 
– mastery of the signs
all- 
-done
Overall, I highly recommend going this route. It can even help with comprehension, as sometime people—even grownups—are a bit mumbly; but adding a sign to your word helps reinforce ideas. Take your time, and don’t try out too many new words at once, and in no time, you and your little ones will likely be communicating.
Good luck!
