Hi skilly
If i've had a good meal in a restaurant I would normally tip 10% of the bill, so if it's 100 lira then 10 lira is sufficient.
If I'm just paying for drinks in a bar I would still leave a few lira tip - depends how much you've spent though (and how drunk you are I suppose

)
I just feel that the guys working in the resorts don't earn much money for working so long and hard in that heat - and I know all tips are very gratefully received.
All tips are put into a "tip box" normally kept behind the bar, which is opened once a week and the tips shared out between all staff.
Hope this helps
Mazz