Although completing the course modules and lessons in order is highly recommended, you can access any module or lesson at any time. The freedom to move throughout the course allows you to fill in your own knowledge gaps however you choose and to skip any material you already understand. However, you should complete all project assignments regardless of your previous knowledge or skill level because each activity is designed to unlock one of the core artistic principles that you must master to progress in your artwork.
Also, make special note of the EXPERT TIPS in each topic or lesson. These tips are hard-won pieces of advice discovered after many years of trial and error.