How can I strike up convos with customers as an autistic person?

Hey y'all! I was recently hired as a broista and I did my first training at the window today. When getting feedback at the end of my shift, my trainer mentioned that I should prob be chatting with the customers more (but otherwise I did well). Now I did fine with the basics (is this your drink, do you want a straw, etc) and when the customer had something obvious I could compliment, but I couldn't really talk when there wasn't something like that to fall back on. As the post title says, I am autistic, and initiating casual conversation is extremely difficult for me. I kind of need a script to follow, or at least a place I know I can start! Despite my best efforts, I've been spiraling about it all day, and I'm trying to convince myself I can do this job. So what are some of your tips for starting and maintaining conversations with customers?