Hi! I'm going to use this post to collect some of my favorite resources from classes to articles; technical and big-picture. I'll add to this over time.
Quick personal aside, feel free to ignore:
My audio experience when I graduated under-grad was very learn-by-doing, self-taught, and taught by those who had self-taught so I had pretty much no technical language to talk audio and no formal training. This was kinda frustrating for me since audio tends to be a bit of a boy's club and, while practical studio experience is (I think) widely valued over academic experience, I often felt like I was faking my way through it all and that my knowledge wasn't valid.
That's why I started grad school at Belmont (their M.S. in Audio Engineering program), because I wanted to match some formal training with what I currently had going on. It turned out that program wasn't a great fit for me and I'm kind of taking it semester-by-semester (especially during COVID-19), taking classes that I think will benefit me, since the overall structure of the Master's program, if I followed it exactly, would take me down a career path I'm not super interested in. [Feel free to message/email me if you want thoughts on audio grad programs]. Due to that experience (and based on conversations I've had/my attempts to find internships and get my foot in the door in the Nashville audio scene), I would generally say that a good mix of practical experience (wherever you can get it), combined with personal research is the best move.
By that I mean, get scrappy, find somebody who will let you shadow them, find a studio that needs spare hands, find a buddy who needs an album mixed, and give it your best shot. Then when you come across stuff that doesn't make sense, plug-ins that have words you only vaguely understand or nobs that don't seem to do anything, a) play around and see what you can figure out relying on your ear and intuition, and then b) research! Google "compression vs. limiter" or "what is a pre-amp" and get rolling.
Mixing + Podcast Editing
Omni Sound Project (online workshops/events) - I have learned so much from these during quarantine life.
LinkedIn Learning: Pro Tools -- I haven't done it personally but I hear rave reviews for this.
Sound Design
The Creative Guide to Sound Design (article) - for all you audio fiction fans
Digital/Content Marketing
Hubspot, Content Marketing (course)
Hubspot, Content Strategy (course)
Hubspot, Content Marketing Certification* (course + certification)
Hubspot, SEO Training Course (course)
BONUS
I highly recommend making a "binder" (which for me is just a google slides doc) with pretty much everything you learn in one place. My "studio binder" has a slide for each microphone I own and their frequency response, pattern, any other relevant info, as well as a slide or two for different plug-ins and effects I use often. Leave notes in this lil doc whenever you add something to your ~toolbox~, as they say.