What Am I Doing Wrong

I work at a diner known for organic, fresh food. Most of my guests are from a middle to upper class background, with many being straight up wealthy. I am an experienced server with many regulars and have been promoted and will likely be promoted again.

I have noticed that while many of my coworkers often receive overly generous tips ($50-$100), I rarely break $30 from a table. I have tried many approaches to serving from being relaxed and jovial to being professional and attentive yet not obnoxious. I’m regularly asked my name and praised. I always refill before the drink goes dry, drop off condiments and extra napkins before the meal, pour the coffee and water for guests… I have no clue what I’m doing differently to not make what other servers do. Of course I make mistakes from time to time (forgetting a refill or not prebussing) but overall those mistakes happen in the busiest rushes and it is usually corrected within less than couple minutes.

I suppose I’m asking what other servers who always get above 20% do that I don’t. What is your demeanor? What little things to do you do to stand out to guests? It’s really getting to me and making me insecure.