Well you are never going to get a lift free set if you don't get that cuticle of.
do you use a cuticle removing gel or just the NSI tool?
I have trained with NSI and I have to say that while I consider them to be a first class company I would never consider working on a client without my creative cuticle remover. Its IMO the best on the market and so long as you give it the time to do its job I have never met a cuticle that could stand up to it.
Unfortunately you haven't filled in most of your profile so we cant see how long you have been qualified but for things like shape of nails etc I strongly recomend a 121 session with a good trainer. It might seem like a lot of money but I can honestly say that my first 121 earned his money within the first 15 minutes of our day.
Finally, nail biters are the worst, if you think they leave their acrylics alone, you are sadly mistaken, your work will never look its best with a nail biter, but on the plus side, every other client is a piece of cake after them.
Also your time doesn't tend to get better until you are doing several sets one after the other, some things need to be repeated until they become automatic in order to be quicker. and get in the habit of talking to your clients hands not her face lol