One for the parents

This post is about how you learn your first language as a child.  This a good one for parents to read.

Exercise your articulatory muscles
You do this by babbling.  Note that all cultures babble and it is not only normal, it is a necessary part of language development. 
Even if the child's first language will be sign language, they will babble; they babble with their hands.  In their case, the articulatory muscles are in their hands and fingers.

Copy the sounds
Keep in mind here that children understand more than they can express.  This is proven with kids who can use signs to express their requests before they can ask for milk and the amount of gesturing that kids use in general.  My daughter used a hand and sound gesture to point out planes well before she could articulate the word "plane".

Kids learn nasals and voiced stops (see the IPA chart here) first.  These are the "b", "g", and "d" sounds. 
The fricatives and liquids come last.  "s", "z" and "y" sounds, for example.

What is interesting is that if you get to know the IPA chart, you see that children are actually approximating words using the sounds that they are familiar with first and you can translate these approximations.
Can't say Zebra?  Says Debra
Can't say see?  Says Dee

Understanding how kids approximate words they hear using the sounds that they can already use may just help a lot of frustrated parents out there figure out just want the screaming toddler is upset about.

What about correction?
There is a lot of evidence that correction does not play a big part in First Language Acquisition as adults tend to correct kids on factual not grammatical errors:
Child:  There is five chairs!
Adult:  There are SIX chairs
Not:  There ARE six chairs.

And, children can be oblivious to correction anyway, at least to some extent:
"Child: Nobody don't like me.
Mother: No, say "nobody likes me"
Child: Nobody don't like me.
(eight repetitions of this exchange)
Mother: No, now listen carefully; say "nobody likes me"
Child: Oh! Nobody don't likes me."
McNeill, D (1966). Developmental psycholinguistics. in F. Smith & G. Miller (Eds.), The genesis of language: A psycholinguistic approach (pp., 69-73). Cambridge, MA: Massachusetts Institute of Technology Press.

And yet children still learn to speak despite our terrible teaching.  The human brain is a truly amazing thing!