Good question Flaps. Great actually.
From the pax point of view, lots of things but just to be awkward they don't all apply at the same time! Mindreading skills are therefore essential LOL
Smiling is a great start!
Being friendly and approachable comes a close second
Taking care not to bash pax elbows with trollies/self is nice
Basic politeness "would you like some tea sir" is sooo much nicer that "tea?"
Speaking slowly and clearly enough on PA that we can hear what is being said and act on it if required.
NOT treating pax in economy class like cheapskating scum (I can't help it if my company decides we will have an economy drive and give up flying business for a while). So no scowling please.
Trying to help when problems do occur - reassuring us that everything's ok when we do dumb things / can't work the IFE / spill our drinks etc
Not appearing to mind if we ask for another pillow etc.
Letting us know what's going on e.g. if we are delayed, why?
Basically going the extra mile and treating people like passengers and not SLF.
At the end of the day though, provided everything goes ok, pax don't see the FAs as anything other than waiters/waitresses. And good service is absolutely vital. Sorry if that seems harsh but if the service is awful, we don't enjoy the flight. I hope never to find out how well they have been trained in safety matters.
Best FA I ever experienced was an Italian guy in BA economy. Worked like a one armed paper hangar. Nothing was too much trouble. Totally dedicated to pax comfort. Brilliant.
The worst - A CSD on Canadian who gave an almighty earfull to pax who fell asleep / dropped newspaper on floor, causing 'an unacceptable hazard to my crew'
Could go on all day but that'll have to do for now!.
CS