1. Establish /l/ in isolation and single words first: http://www.speechandlanguagekids.com/how-to-teach-a-child-to-say-the-l-sound/
2. Write out /l/ blends words with the /l/ blend letters on separate cards
3. Build up the word from the back to the front (start without the /l/ blend, then add /l/, then add the first sound)
4. Work on single words until the child can do spontaneously
5. Work up to phrases, sentences, and conversation as usual