The two hardest things to do in snowboarding are getting through the lift line and getting off the chairlift. The lift line is tricky because you have your front foot in the bindings, and your back foot out of the bindings to push. If you get in to a hurry your legs can part ways real quick. So take your time and get a good feel for moving with one foot out of the bindings.
The chairlift can be tricky when getting off because you still only have your front foot in the bindings. The key here is to confidently ride your snowboard straight off the chair. Treat the chairlift ramp like it's an actual ski run. Get a stomp pad and practice riding with your foot on it.