I misgendered someone for the first time

I don’t live in the most progressive city, it’s more a tourist town than anything. Needless to say I still respect others and their personal preferences to how they wish to be addressed. I just don’t always realize/remember that there are others who may look or sound a certain way however that doesn’t always correlate over to their preferred gender identity. I am learning and growing. Anyway, I was at a cafe yesterday and ordered food and a smoothie. The smoothie came out first, I grabbed it and sat back down. Someone else brought out my food and delivered it to my table. I said “thank you sir!”, and they meekly corrected me saying “oh it’s ma’am actually”. I said “I am SO very sorry, thank you for the food!” I couldn’t even look her in the eye at that point I was so embarrassed. She said “it’s okay!” And went back to work. Very nice person, I simply have never been in that situation before.

I sat there the whole time eating thinking about how I have to word things differently moving forward with anyone I meet.