There are "track days" and there are High Performance Drivers' Education (HPDE) events, and there are car control clinics.
If you are a newbie, and I think most questions here are posted by newbies, your car left the factory ready for anything you are going to throw at it for HPDE and/or car control clinics. Your brake system absolutely need to be equipped with plenty of brake pad thickness, with brake fluid which is not older than a year (brand new is best), the factory seat belts for driver and instructor need to be in excellent condition, and your tire condition and air pressures want to be correct. And your lug nut torque should be correct.
By the way, in my mind "track" means something different from eighth mile or quarter mile straight line events.
For HPDE events and for Car Control clinics I think most people obsess about prepping the car rather than prepping the driver. HPDE events will likely have you and your car on track for three to five sessions of 20 -30 minutes with an instructor aboard for newbies.
Car control clinics you will usually be involved in lots of slow speed maneuvering in such things as skid pad work, both dry track and wet track. You will likely be doing lots of slalom work, and MAYBE a full autocross course. Most of those events are going to have speeds no higher than highway and back road speeds, with little heavy brake work. Some events, depending on where they are held, may include a few laps on a race track with an instructor along side.
HPDE events will have you in some sort of track environment ,on track with an instructor in your car On HPDE events you will be going at speeds higher than normal highway speeds, and you will be using your brakes hard, in order to get down to safe cornering speeds. Your brakes will get hot. They will not get racing hot in any run group which has you required you to run with an instructor. Relax about brakes, focus on what is inside your helmet.
Once you get a few days behind you and move into run groups with no instruction your car may be ready for mechanical upgrades. Now you are getting to track days.
PLEASE NOTE (my opinion follows):
If you are indeed a newbie, stay away from events like Sports Car Club of America{(SCCA} "Track Night in America". You and other drivers on the track at the same time as you are not experienced, and with no in-car instruction, participation is neither smart nor safe. You will learn nothing about correct hand position, accelerating technique, MIRROR monitoring, braking, MIRROR monitoring, turning....nobody is going to be watching your eyes, and where they are focused as you are on track, or in the pits.
Some events will sometimes have fewer instructors and start of with "lead-follow" laps, where newbies follow an experienced leader, and track side potters can see who is doing what in the formation. Never done one of those, have no experience.