During the wait...the wait for auditions, you must make yourself useful. I've learned to exercise as much as possible, do administrative work, expense reports, cleaning up my hard drive, write thank you notes and send gifts, update website, update all acting profile, tackle social media, write blog post, send email updates to colleagues and friends, work on creative side projects, and work on my side hustle, which is selling clothing on eBay.
These are all things that contribute to your business. I find that updating online profiles, resumes, and websites to be the most beneficial. Once the time comes where you need an updated resume for a callback, you already have it and simply need to print it out. Online profile updates are important because if casting directors, producers, or agents want to view your work online, then its current. Its just the professional way to keep things. Updating websites goes along with this.
I find that because being a self-employed actress is so time consuming and kinda like an ongoing thing, taking a break for a bit to rest and enjoy life some times is necessary to lead a balanced life. Its like vacationing at home. On those days, I allow myself to do absolutely nothing, watch TV, cook a new recipe, and organizing my space in different way.