I never waxed up an incisor, in my school, the very first tooth wax-up (along with first competency) was #20 and let me tell you, that was a hard tooth to begin this skill.
I remember back then, I thought my dental career was over, I used to feel "I'll never be able to produce a #20". Anyways, what really helped me was getting our instructor, and had him do a wax-up model of #20 (from start to finish) infront of me, so I can watch his technique.
IMO, all of dentistry is 70% technique, and 30% natural skills. You need to watch someone do one, so you can develop the technique of how to apply the wax, how to shape the wax, and how to contour the wax. Pay close attention to which instruments they use and how they use them.
all the best