Firstly, each company has their strengths and weaknesses, however starting out today is great, as no company makes a truly bad camera anymore.
*I learned the importance of composition by using primes.
*I've learned that just a simple white board can make a huge difference. (diffused bounce light)
*A mono-pod acts as a stabilizer when not touching the ground.
*The more buttons the better
*Carry a color chart, take a picture of it before you start using the light you will be using. You now have correct skin tones.
*Don't carry to much, you cant use it all at once.
*Speed lights/flash gun: Life gets better, you control your own light, don't be intimidated, just try it.
*Good camera straps: It makes life so much better.
*Good walking shoes: Your feet will thank you
*A light meter: Your cameras light meter is pretty good, but an external light meter makes it real easy to dial in flash.
*A good Mono-Pod: as stated above, when retracted to not sit on the ground while hand holding, it acts as a stabilizer, it dampens your movement.
*A good tri-pod: When you are doing long exposure, you don't want a light breeze to be making the camera move.
*A good camera bag: Make it so carrying your gear is comfortable!
No/Yes: Find out what you want to add to your skill set first. I would have to say the first thing any new photographer should do is stop relying on zoom. Get a prime, and move your body to get your desired shot (not an option on a fixed lens camera, but rely less on zoom if you can). Focus on getting your scene framed first, and keep experimenting.
Second: Light, too many people Do not even try to work on their light, but rather give up the lazy excuse "I like to work with available light" NO, master light, it will set you apart. Just a big piece of white cardboard with a big light pointed at it, and having it reflect a nice diffused light out on your subject can make such a world of difference.
There was a recent cars & coffee I went to and there was a gentleman with a Sony a6500 who was looking down on me as I set up my speed lights and tripod. He scoffed
Well I didn't see his pictures being shared.