I can give you some ideas we got from our speech therapist...free of charge!
~Massage his tongue with a toothbrush.
~Let him chew on those baby chew stuffed animals that have different textures on them....rubber ends.
~Read to him for a minimum of 15 minutes per day.
~Talk to him constantly...describe everything in detail...for example-when getting him dressed...we are putting your red shirt on over your head. Now we are putting your arms through the sleeves of the red shirt. Next we are putting you blue pants on...one leg at a time we put your blue pants on. etc.
~Repeat back to him in 'proper' terms...example if he calls his bottle ba-ba...say yes that's right that is your bottle...very good you said bottle.
~Give names to everything...that's a tree and point to it. If he points to something, give the name. That's a street sign.
Good luck...