Who do you tip and how much?

[hmmSleep]

So, I normally, (unless service appalling) tip in restaurants, taxis and hairdressers.

Other times I'm not really sure if I'm supposed to or not.

Do you tip the following -

Supermarket online shop delivery men?
Delivery men in general?
The person that washed your hair at hairdressers?
Binmen at Christmas?
Postman at Christmas?
Hotel porter?
When you order a round of drinks at a bar?

I tend to, just because I'm not sure if it's the norm or not, but sometimes get very funny surprised looks!

Supermarket online shop delivery men? no
Delivery men in general? no unless its really big furniture that they have had to struggle with
The person that washed your hair at hairdressers? usually
Binmen at Christmas? no they unhelpfully leave crates and bins blocking the drive week in week out
Postman at Christmas? yes our postie is amazingly helpful
Hotel porter? never stayed anywhere posh enough to be offered the services of a porter
When you order a round of drinks at a bar? used to when i had a "local" pub

Ooh, I obviously tip too much! Although haven't done an online shop since moving out of a top floor flat, used to feel bad making the delivery men carry those crates up 6 flights of stairs!