When you're out with someone who used to wait tables, you can almost always tell. "Could I please have a water whenever is convenient?" she might ask the server, leaning over the table with a giant smile. Former servers always tip 20 percent — and sometimes 30 percent. They have a zen patience about kitchen errors, accepting a cheeseburger even though they ordered avocado toast. Sometimes it's good to take a break from thinking about what you want from a restaurant in order to consider what servers wish you knew. So we asked! Here are tips from pros across America.

Illustrations courtesy of CopyPress

There's a reason those who worked in the restaurant industry feel so strongly about a gratuity of 20 percent or more: By and large, servers nationwide are making very little in base salaries. "The assumption is that we make minimum wage, which is not true," one Boston server, who has waited tables for 20 years, told us. "I make $3.35 an hour." Mic drop.

Hands off, diners! It may be obvious to you, but "don't grab my arm to get my attention," moans one New York City waiter. "I ... hate that." (Remember the one boss who used to make a point by grabbing your arm or patting your back? Yeah.)

Decide to spontaneously waltz out for a fancy dinner at 10 p.m.? Good for you! But did you find a place five minutes before it closes at 11:00 p.m.? Maybe take a breath and reconsider. "If you come into a restaurant at 10:55 and order a three-course meal," says one San Francisco server, "it will make the kitchen staff want to murder me." Think about it: You've just added an hour to the time when everyone there gets to head out for the night. You are not likely to get the most-tender service.

You love your regular spot. But was your last date here the one who snapped for the waitress? Did you book your table online using OpenTable or Resy? Well, your next experience here might be ... different. Someone may have noted your date's behavior under your name. "It's usually positive," says our Boston waiter, such as "This regular enjoys a filet," but he's also seen "very negative things," such as "poor tipper," "camped out" or the euphemistic "particular." He says, "I would be defensive, for sure" if saddled with a "particular" patron's table.

Making small talk with your server — "How is your day going?" — is a pleasantry most staffers appreciate, but avoid the dreaded question about "what else" he or she does, moans one San Francisco server. Consider the fact that waiting tables is exhausting. Consider that often — as long as you tip well, natch — servers make decent money waiting tables. Consider that these days being a server is a career for many in the industry. Then you'll understand why this can sound egregious.

Although management doesn't always allow them to tell you this, "bartenders would love not transferring tickets to a table," says one seasoned server. Remember that "servers tip out everybody at the end of the night, and your 20 percent goes to the food runner, busser and bartender." If you have a drink at the bar while waiting for your table, it's a mensch move to settle up your tab.

Although it's fine to "make a little check-mark-in-the-air signal" from across the room if your waiter makes eye contact and you want your check, says our Bostonian, "don't interrupt a server when they're at a different table." You're interfering with the fourth wall that makes restaurants feel like magical places: "You want to give every table the impression that you're their only priority," he explains. So resist the urge to lean over at those oh-so-closely-set-together tables (even if you already feel like you're part of the same party)!