The thing that helped the most was consistency and always going to the same restaurant. Once he was able to achieve a successful experience in that restaurant then I would add one new one and work on that place while also going back to the familiar one too.
Trenton got really good at restaurants about a year ago. However, this past August/September he declined big time. Trenton went into a regression. His normal routine was thrown off a few times, school was added into his schedule, etc. Therefore, everything went downhill. One of the things that declined was his behavior in public, such as a restaurant experience. Even though he went through a very difficult phase, I was still very brave and tried restaurants. We didn't last very long on some days. He would sit down at the booth and scream repeatedly. He would go into a meltdown, hit, and try to escape, etc. Therefore, for a many weeks I stopped taking him out in public. He needed to get his routine and behavior under control before we could master our public restaurant experience.
Slowly over time his schedule got back on track, he got used to school and his new schedule. Therefore, I slowly introduced his familiar restaurants to him. He started achieving them again! FINALLY!!!
Today, he went to a new place and loved it! I had a birthday this past week so my parents came up today to take us out to eat. I had Andrew pick my birthday lunch and he picked IHOP. As always, I am so proud of him. Every thing is baby steps with us and sometimes we are forced into regression due to life happening but we slowly make our way back to where we were! I am happy to report that T-man is doing well in restaurants, again! (FYI......well for us would probably be bad to most people. He vocally stims and is impulsive, and fidgets but we make it through!)