Here are three quilt block tutorials that I put together for the Boston Modern Quilt Guild BOM.

These tutorials all have improvisational techniques, but they also let you be a little precise if you want to be.

This tutorial lets you practice curved piecing: Curves Ahead

Curvy

With this one you can try paper piecing without worrying about things being too perfect: Playing with Paper

And this tutorial lets you improvise with strips of fabric: Fenced In