I sometimes have questions not so much as to when to tip someone (not necessarily a bartender), but how to go about it.
We're all used to tipping waitstaff. You leave the money on the table, or add it on your credit card receipt (although I always prefer to tip w/ cash, except if it was a business expense).
It's easy if there's a tip jar too, that is if you're going to leave them a tip.
Actually, that's a related question to throw out there...do ya'll normally put money in a tip jar, sometimes or never?
I've done it, like a buck, if I feel the person waiting on me was friendly (not overly friendly), was attentive and in some tangible or intangible way I felt s/he went out of their way for me.
However, let's say I go through a drive through Starbucks, or even walk in. The only thing I ever get is a straight black cup of coffee to go. I don't think taking a paper cup out of a stack, pouring coffee in it and putting a lid on it warrants a tip. If I went in and ordered multiple fancy drinks, I'm thinking I'd leave one in the tip jar.
Hairdressers..for me there's always this semi-awkward moment (I'm sure it's entirely on my part) where I give them my credit card, with money on top if it, obviously for them. Where I go now, my hairdresser walks up to the cashier with me, or sometimes is the one who checks me out.
I used to go to an Ulta for my cuts, and there you pay at the resgisters up front, while the salon is in the back. I was in the habit of giving the stylist a tip, and paying the balance up front. Each time the cashier would ask me if I'd like to add a tip, and I'd tell her I already took care of that. Once or twice, for reasons I can't remember, I hadn't given the stylist money, and when I told the cashier I wanted to leave the tip in cash, she gave me a separate envelope to put it in. I don't know, that just feels weird. I think my problem is that one develops a relationship with your stylist...like paying someone to be your friend (sort of friend).
I've never had to deal with parking valets, not to sound like the little lady, but the man I was with would take care of that....seems like guys always (if they live in the city particularly) always have to have singles at hand.