I have two rules that I live by in my sewing: 1, when making a pattern or garment type for the first time, make a muslin. 2, make the lining first.
Whenever I make a garment, I reverse the usual order of the instructions and I make the lining before I make the outer garment. There are a couple of reasons for this. I don't know about you, but I sometimes suffer from "project fatigue", and if I don't make the lining first, by the time I get to that stage, especially if it's been a difficult garment to make, I may lose interest and put it in the UFO pile. By making the lining first, I avoid this.
The second reason is because the lining then acts as another muslin. This is especially true for dresses and tops. I can try it on and tweak the fit if need be, and then transfer any changes to the outer garment before sewing it. It's a minor change, but it can make a major difference. Try it and see!