Tipping

I find it easier to tip waitstaff,bartenders and standard taxi drivers then it is to tip hotel folks, hairdressers, car drivers (when its a work trip),  etc  - the first being that you can do it pretty easily and its non embarrasing to leave money on the table or add to the bill or to say to a taxi driver - just give me 2 back or whatever-

But for the latter, I find it quite awkward and embarrassing - like "Am I doing this correctly" kind of thing...  and I fumble and feel strange by it all...    

I always pre-tip the concierge at a hotel - It makes me feel metropolitan.

"Hi, is it Edward? Look here's a little something...I may need you later on. Thanks."

Give it to him very discreetly.

Whenever you go or return - make quick eye contact with him and give a little nod.

I'm not sure why this article came up on the Guardian today seeing as it's from August 2012, but I thought it was quite fitting.   

http://www.guardian.co.uk/lifeandstyle/wordofmouth/2012/aug/17/the-website-which-names-lousy-tippers

Apparently, this will be the answer of what to do:
http://www.guardian.co.uk/lifeandstyle/wordofmouth/2013/jun/17/guide-tipping-restaurants-holiday
But not why. Apologies if already posted.
And the consequences?
http://www.bbc.co.uk/news/magazine-22969465
Apologies if either already posted.