A lot of it depends on the child's learning profile - do you know his/her sensory strengths/weaknesses? For example, my autistic son is a highly visual learner, with an auditory processing disorder. We used a LOT of PECS to start with (http://www.do2learn.com/ has a lot of free ones, as well as other good special needs resources) while teaching my son to read and communicate. Now that my son is a proficient reader, we do almost everything in writing, because it's so much easier for him to process. We also bought books on Montessori education, and prepared Montessori materials for him (we chose Montessori because she developed her materials working with special needs students; the materials are very tactile, and there's a strong emphasis on learning independence, self-regulation, and social graces in Montessori. This ebook is a good start: http://www.montessoriathomebook.com/).