I hope I don’t regret answering this. The decision to do autocross versus HPDE track day (HPDE = high performance driver ed) depends on a number of things, including your goals, like competition, improving your driving skills, go 100+ mph legally, driving a race car, or simply driving on a race track in your own car, and time. It’s difficult to advise you on a path without understanding what you actually want.
While both are very fun, Autocross is considerably less expensive than a HPDE track day,. It’s also much safer, but it’s slower, and seat time is limited. There are many clubs/organizations that offer autocross that might better match your goals than others. Do your research .
For example, for HPDE, some clubs focus more improving car control skills, while others try to steer you toward racing, ie their club series. For autocross, SCCA Solo II is competition focused. Lots of rules, regulations and different classifications, very strict on modifications, and they severely limit how many runs you let you do. On the opposite side of the autocross spectrum is NICO, which is very informal and geared strictly toward fun. With no limits on the number of runs, no classes, no restrictions on mods and free coaching. Again, it boils down to what you want to get out of it.
As far as what you should do before hand? Once you figure out what you want, the most important thing is determine what you can actually afford. If you’re thinking doing HPDE/track days, (many events are 2 day) you’ll need to add up the event cost itself, transportation, lodging, gas, food, track day insurance (which are typically declared value policies, so the higher price you set for payout, the more expensive the policy) , the helmet, making sure your car can actually pass the technical inspection. Every organization provides their tech requirements, and many require a mechanic/shop confirmation, which can cost money too. Not something you can skimp on. And all of them do inspections before they allow you on track.
Regarding some of the other stuff you mentioned, prowess at a video game will not give you a big advantage on a real race track. Better to just simply go there with an open mind and not boast about stuff like that as you’re going to find out very quickly how much you need to learn. Gloves and/or driving shoes are not usually required, especially for newbies, so unless you know for sure you’re going to do multiple events, save your money until you know this hobby is something you can/want to do again. My recommendation for helmets is to never skimp (ie don't go cheap). Your brain might be your second favorite organ, but it’s critical to protect it.
If you're seeking recommendations on your direction, given your young age, I suggest you try to find a local club autocross event. Marque Clubs tend to be more relaxed than SCCA, offer more seat time, with fewer restrictions and is far easier on the wallet. NICO’s annual Carlisle autocross is an example of the type of event that I'd recommend you look for to try to help figure out your goals. It's a Friday-Saturday event. We have people from all over the country that attend every year from places farther away than Florida. You’d not only meet a lot of people you already know at NICO, many of whom are experienced autocrossers, and a few road racers that happily offer free instruction and ride-alongs. There’s even an old track instructor that might to jump in and offer tips (ahem). Some of the folks that travel long distance rent cars which are allowed, Some of them actually drive their cars all the way. The event is also part of a giant car show (Carlisle Import and Performance Nationals), so there are always very interesting vehicles around, plus there's an audience throughout the event. It's quite unique. The event also features drifting which is a hoot, and some of those drivers offer ride-alongs. Here’s a link to the event if you're interested. There should be an additional link to sign up that contains our technical requirements. That might give you some idea what other clubs expect. Here's the link.
https://carlisleevents.com/events/event ... +nationals
If you’re looking for clubs that offer events at Sebring or other close venues, check out motorsportreg.com
https://www.motorsportreg.com/
Motorsportreg also has links to driver school insurance links.
Enjoy.