If you're just starting and wanting to invest piece by piece, I've put them in the order of priority I wish I knew about when I was starting out:
Diva Ring Light (if you're just getting one light THIS is the one to get, hands down)
Note: I recommend this tripod because the first one I got couldn't withstand the weight of the light plus the iPhone mount.
Soft Box Additional Lighting - Above my head angled down toward back wall (not imperative but it does make a difference)
The Diva Ring Light is all you need but if you want some different options, I started with all of these and still pull them out from time to time.
Small Ring Light - for phones (great flexibility and grip)
Whenever I use my iPhone headset or Air Pods, it's FINE (it's better than not speaking into a microphone) but after trying less expensive studio microphones, I finally got the #1 recommended, and it makes a world of difference.
Blue Yeti (there are pricier / higher quality microphones but if you're just starting THIS is the one to get)
I've been doing online work for over a decade and through trial and error, and a few great companies who have come along, these are the best choices to start and grow with:
Squarespace would be my second choice if I didn't offer online courses. It's sleek and has great templates to choose from.
With that said, Wix was my company as a Spa Owner for years.
From there, I switched to WordPress with a variety of plugins for a few years before Kajabi came along as an all-in-one solution, thank goodness.
ConvertKit - just start with this instead of MailChimp or one of the bajillion other options, it's a great choice to learn and grow with. Note: Kajabi DOES offer email but I have amazing results actually landing IN people's Inbox with ConvertKit, which is what you want.
Glass White Board (this is the one you see in some of my videos)
Alexa (this is the one I have and love but it's their 1st Generation and you can only get it used - the speaker sound is amazing)
Alexa Show (pretty good speakers, I actually have this one in our bedroom)
TubeBuddy - this is a YouTube add-on and helps define tags and analytics
Calm App (I use the Sleep Stories almost every night)
Insight Timer (I've been using this timer for years - especially great for meditation)