This post is about pinning in general - while I do talk specifically about The Violet Quilt Pattern, these tips can be applied to any patchwork project.
I am a big believer in pinning when piecing your quilt blocks. If you pin, you will get better results than if you don't pin. There are lots of different pin options out there, but my favorites are these Clover Fine Patchwork pins. They are very thin and slightly flexible. They also hurt like @#$* if you step on them, so I don't recommend that.
You may not be as zealous about pinning as I am, and that's fine. I've said it before: I'm not the quilt police. However, my method gets consistently good results so I am going to share it with you and you can use it if you wish. If you don't want to go quite this crazy with pins - at least pin at the places where you have seams that line up - that is the most important place.
When I pin (and I pin EVERYTHING that I piece) I place a pin at the beginning/end AND at every seam intersection AND every 2 inches. It is a lot of pins, but I just turn on an audiobook and pin a big batch of pieces at once. It is one of my favorite parts of the process.