Applied behavior analysis (ABA) is the most common therapy for children on the autism spectrum. ABA has been shown to help children on the spectrum (from mild to severe) develop needed skills and minimize undesired behaviors such as self-injury. Its effectiveness is backed up by hundreds of studies.
ABA now includes a range of different approaches. This article from the Child Mind Institute describes how they work and how they’re different, and concludes with links to additional readings on ABA.