When people ask me how autistic people can learn to make friends, my answer is always to become involved in activities that focus around special interests.  Researchers led Robert Koegel at UC Santa Barbara created interest-based clubs that allowed autistic boys to develop strong friendships:

Koegel offered the example of a student with ASD who has a keen interest in computer graphics. The team created a graphic design club in which students would design logos for various companies and businesses. Because most of the students lacked the necessary expertise, they depended on their classmate with ASD to make the venture a success. "When he was able to interact on a topic in which he was interested, he was able to demonstrate more normal social behavior," Koegel said. "He not only made friends with his fellow members, he was elected club president."

Their findings mean that scientists may previously have been wrong that the areas of the brain related to social functioning are damaged in people with ASD:

According to Koegel, the findings are also significant because they indicate a higher degree of brain functionality than researchers had previously associated with ASD adolescents. "It has been commonly believed that the part of the brain related to social skills is so damaged that adolescents with ASD are incapable of normal social interaction," he said. "We demonstrated that not to be the case. Once you can motivate kids to try things, they make dramatic and rapid improvement, which shows the brain is not as damaged as first thought."