Neil deGrasse Tyson estimated that if you collected every beer coaster, cocktail napkin, and bar tab on which someone scribbled their number for a bartender, they’d stretch to Jupiter and back a thousand times. That’s 365 billion miles of digits that—let’s be real—were mostly left undialed.

Even though we invented that very believable statistic, flirtatious customers remain about as ubiquitous as Miller Lite for bartenders and servers. With a well-meaning patron, a little harmless flirting is just that. But as one former server told us, “‘Flirting’ can be defined in many ways, from friendly banter to creepy uncle.” So when is it too much?

We talked to a bunch of servers and bartenders who broke it down for us. Here are their flirting tips for five common scenarios.

Editor’s note: These largely reasonable points of view express the opinions of the servers and bartenders therein. This advice does not guarantee successful flirtation, but may prevent you from being tossed out of the bar.

Scenario No. 1: You’re a flirtatious person, but you don’t mean anything by it.

“It is important not to have any expectations other than a good conversation.” – Stephanie, Edinburgh

“There's nothing wrong with flirting, as long as he or she knows there are boundaries that must be respected—this includes being able to aptly read any verbal or physical cues the bartender is broadcasting regarding his or her own comfort with the situation.” – Mark, Chicago

“Even if the server or bartender picks up what you're putting down, always assume it begins and ends with flirting. … Restaurants and bars can be sexy environments, but we're not sex workers. We are not obligated to respond in kind. Stop flirting in front of your date, and for God's sake—no touching.” – Liz, Brooklyn

“If you are bringing sexual things up, you are straight-up creepy. Go home. Stay there.” – Emily, LA

“There's nothing wrong with complimenting someone. … If the bar patron, however, takes it one step further (i.e. ‘Wow, you must work out a lot,’ etc.) and said server or bartender doesn’t reciprocate, obviously that's [a] problem. – John, Cleveland

“Never refer to your bartender as ‘sweetheart’ or any other overly familiar form of address. It’s not flirting. It’s condescending.” – Anonymous

Scenario No. 2: You’d definitely be chatting them up, if only you could get their attention.

“Never expect a bartender to flirt if the bar is busy. Bartenders are there to do a job, not to stroke egos or pursue romantic liaisons.” – Mark

“Be polite and cognizant of the fact that they have other patrons to tend to. Always tip like a baller, even if it doesn't seem like it's going your way. Leave your number, but don't ask for theirs. Definitely do not ask what they're doing after work.” – Sydney, Chicago

“Just go for it, but don't get too upset if said bartender or server is too busy. They may be interested but actually care about doing their job. Don't take it personally.” – James, Brooklyn

Scenario No. 3: You think the bartender or server is flirting back, but you’re not sure.

“If you're questioning the intention, then the answer is likely no.” – Stephanie

“If the bartender is being courteous but keeping a bit of distance, said individual isn't warming to your song. The best measure I know of is body language.” – Mark

“It is 100% always the server or bartender performing their job until THEY prove otherwise. They will make the move. If you want to leave your number to be proactive, cool. Let them call if they want.” – Liz

“If they're making the kind of small talk you'd have at a bus station, they aren't interested.” – Sydney

“Eye contact means everything.” – John

“If they check on you more than usual, [or give away] a free shot or drink. If they look at [you] while taking care of other customers.” – Rebecca, Chicago

Scenario No. 4: Major swoon alert. You’ve already named your hypothetical first-born child.

“Just don't force anything. That turns creepy really quickly.” – Stephanie

“Picking up the bartender can absolutely be done. If the guest keeps it low-key, it can be a fun part of the job. It's still best to go into [it] with the idea that you'll probably be rejected.” – Sydney

“I'm there to be personal and give you good service, not be a real-life Match.com.” – James

“I've seen both of sides of this coin happen. A [coworker] met her boyfriend serving him and his grandma. They were together for three years. I've had to also, unfortunately, stop serving a man who was making rude comments to a female server. So it's key to know where the buffer zone lies.” – John

Scenario No. 5: You might have become a regular in the hopes of eventually landing a date.

“It's probably a bad idea to hit on a tipped employee somewhere you're a regular. The economics of the situation make it incredibly awkward for the worker to say yes or no regardless of what they want.” – Sydney

“Being super friendly is awesome. Making friends with people who work at your regular spots is also awesome. But while in the bar, don't mention anything sexual. Don't even comment on the server or bartender's looks. They are at work. Respect that.” – Emily

Some of these quotes have been edited and condensed.

Check out more guides to restaurant etiquette:

Who Should Pick Up the Check on a First Date?

A Server’s Uncensored Thoughts on Tips, Tip Jars, and Split Checks