I'm from Europe and I still don't have a good grasp on tipping...
Example: we just ordered lunch for the entire team (7 plates), from a place 10 blocks away.
Damn Libby! cold!
Delivery: I usually do like $4-5 unless its incredibly large or incredibly small
Taxis: always %25 (they need that buck twenty five WAY more than you do)
Restaurants: 15-20% depending on the service, or 10% if you're sitting at the counter
Haircut: %20 and a cool handshake to pass it off
Tattoo: %20-30% depending on how cool the tattoo is and how chill the artist is about it (also you want to be cool with them if you ever need a touch up or another one!)
Bars: $1 per drink unless its a hard to make drink, then $2.
Baristas: change from the coffee.
Seems like everyone has different opinions though, so unless you're being really stingy you should be fine :)
I'd like to build upon what was said. Andrew brought up a good point in that it depends on the services. In Europe, couriers / parcel delivery men can rely very much on their tips from clients. (Addison Lee is a bit different story).
It should be noted, however, that in some countries it may be considered odd or a little offensive to leave very generous gratuity!
Generally, tip from 5-10% at a restaurant and if it's a delivery person from a restaurant, you can give them the 5-10% and it will be at their discretion to determine what portion they'll hand over to the restaurant!
Louie branched off your first post, but I thought it was relevant enough for here.
How much do you tip when you pick up/take-out? I almost never tip, although sometimes I feel very compelled to leave change because I don't want it, but I feel that's ruder than leaving no tip.
Thanks for your feedback! Team Branch