I guess it depends on what products you are using....(L&P, Buff off Gels or Soak off Gels)
I use Buff off Gels and to be fair most of what has been listed above wouldn't do didly to them....i think sometimes when we experience lifting we are eager to find the reason for this and so start thinking of all sorts of things ... much of the time its just down to either the client or the tech and not really anything else....i guess it could be different for anything that is soak off as they are alot more porous.
Clients that nibble the sides if there fingers...this puts pressure on the sides of their nails and cause the product to pop up
Nails that are thin and damaged ... this means that the adhesion isn't as good and may result in lifting
product applied too thick in zone 3 and the side walls.... this can make the product pop up as it should be very thin and buffed flush so as to blend into the nail...almost invisible.
Clients with a very hands on type of job.... lifting, lots of typing, packing ect...all puts pressure on the nails and can result in lifting.