Hi Amber, I used to work in applied behavior analysis for children on the autism spectrum. We would start with words that are highly motivating to the child. For example, if your son loves a certain food teach him the word for that. It’s easier to begin with words that are closely tied to things that highly motivate, so think about what his most common requests or demands are for and start there. ASL is an amazing way to communicate!
I also really like the idea of visual cue cards. Either actual photos that you laminate and put on a board – so that he can point to what he wants – or drawings. I find these help with transitions from one task to another as well. For example, you can lay out five cards in the order in which the corresponding even would happen. First – wash hands Second – eat dinner Third -bath Fourth – brush teeth Fifth – book, etc…We also use these in the doctor’s office to make the intake less scary!