With both girls we used sign language to help them with their communication since we knew speech would take longer to develop. I've heard the argument many times that teaching children sign language will hinder their speech, to that I say you're wrong! I'm sure there is some fancy research out there somewhere but I haven't looked. I don't need to because I've seen so many children learn sign language first and then take off with their speech later.
Teaching my girls to COMMUNICATE is far more important to me than teaching them to speak, initially. But teaching communication is also so important for when that speech development DOES come! Depending on what type of therapist you come across you will hear so many different things about signing in regards to speech development. Some therapists will say to teach children very basic signs such as "more," "all done," "eat," "dada," etc. This is the path we've taken with both girls. Some therapists will say to only teach very specific signs, for example, you shouldn't teach them just to say "eat" you should teach them all the different food signs. Well based on their cognitive development as well as fine motor development when we started signing, we had to start on a more broad spectrum and then get more specific. For example, we started with teaching "eat" and when Zoya got really good with that then we would start teaching some specific food signs such as "banana."
I think just the initial idea of teaching the girls that a sign gets them what they want is so important! "More" has been a really good sign for us to accomplish that with both girls. We've already seen decreased grunting and yelling and frustration from Mila because she understands that she is communicating her needs effectively. This makes her happy. Mila, like many babies learning sign, started using "more" for many things that she wanted (like when she wants my phone or a certain toy), but it was effective and we will expand upon that. They say it's like baby babble. When babies start babbling they babble the same sounds to communicate many different things until their speech develops further. This is "sign language babble." Don't google that term because I just made it up haha.
Here is Mila signing "More" and then "Eat." She started by needing hand over hand prompting to sign both of these words. She got really good with "more" and I would request that she sign "more" for bites of her snacks and meals. When she got that down and was doing it without prompting, I added "Eat."
Then she learned to sign "More Eat" all together. Today she was signing "More Eat" with no prompting from me (other than just waiting her out).