I only have a few minutes free, but I wanted to just mention a website that I have found interesting and helpful on my freelancing journey.
It is http://thenuschool.com/
Created by designers, it is a wealth of information particularly valuable to newer freelance illustrators and designers. They offer tutorials, newsletters, and advice, but I found their blog particularly interesting.
I love the way it's laid out, and the posts offer information on everything from finding new clients, to writing contracts, to blogging, to pricing strategies.
This last I think could be invaluable because they don't offer the kind of advice on pricing that you've likely already found on the web (you know - those ones that basically tell you you have to ask the same questions you're already asking and coming up blank with), nuschool offer useful, brass tacks, actionable ideas on how to break up your work and price each piece of it.
Their writing is simple, down-to-earth, and relatable while also containing lots of nuggets of usefulness and, being created by designers, being really attractive too! I've been reading articles of theirs that are barely relevant to me, just because I enjoy reading their writing!
Really interestingly though, are their articles on things that might seem a little less obvious, such as managing your life/work balance and advice on how not to let your illustration career consume you.
The cherry on the top for me, were articles on things like self-promotion for introverts, and freelancing with depression. These are things that maybe wouldn't occur to a lot of websites as a valuable resource, but I think that for the right person, these articles could be a really boost and source of inspiration and a reminder that they can do this, and they are not completely wrong for trying.
Check them out, if only just to enjoy the website design!