I don't have major heartburn about new vs used and the pro/cons of either, personally. It's really up to you to decide what's the right fit for you. Ask 100 people, get 100 answers to this one. In the end you're choosing (generally speaking) between:
New car:
Warranty if things break.
Higher cost / payments
Depreciation of value
More advanced safety features and tech (pro)
tech (con)
Used car:
Lower cost/payments
Someone else ate the depreciation so you won't have to
No warranty. If it breaks, you're eating the cost of whatever you cannot fix yourself.
Older cars have less modern safety features depending on age and laws.
Less life left in them, especially if you live some place that sees a lot of rust and road salt.
Things to consider:
1. What is your budget?
This includes things like money for a down payment, what you can afford to pay for financing, as well as care and feeding (gas, oil changes, tires, other routine maintenance) It also includes things like your insurance and registration/taxes. Newer cars will have higher insurance costs and registration than older cars, and insurance is ageist and sexist. Males under 25 and old people pay the most, and by a LOT. You need to have a hard look at your cash flow and decide what you can afford BEFORE you shop. If you decide to finance, check your bank / credit union / loan shark and try to get pre-approved before you buy so you can make a purchase confidently and know your spend. Financing through a dealership is risky and generally costs you a lot more in the long term, but sometimes, it's what you have to do. Especially as a first time buyer with little or no credit history. So back to the "what can you afford?" question. Do not overextend yourself. Have a number. Stick to it. Walk if they won't work with what you can afford.
2. How much do you drive?
The more miles you put on a car, the more often it needs to be serviced. On used cars with higher mileage, this may also mean much higher chances of failure sooner. If you're just running to town a couple times a week and the like, a higher mileage used car isn't as much of a risk as if you were putting 50 or more a day on the clock. On the flip side, if you're putting 12k or more miles on it a year, the comfort of a new car warranty is something you should consider. Cars break down. New, used, even right off the dealer lot. Who pays for that repair matters, and you need to consider that.
3. How handy are you with auto repairs?
If you can fix most minor and some major things on your own, you have a lot more flexibility buying a car that may or may not need some work done soon. That can translate to a cheaper buy up front on something used or that needs repairs. If you can turn a wrench confidently, it's sometimes easy to pick up a "broken" car that needs a couple hours of work for dirt cheap.
4. local purchases (marketplace, craigslist, "I have a buddy", etc...)
If you are not mechanically inclined and a good bargain hunter, just don't. Assume every seller is hiding major damage in a car they're dumping unless they can prove otherwise. Take a mechanic with you or do not agree to a private sale without taking it TO a mechanic of YOUR choosing inspect it. Trust no one. I'm not saying there aren't good sellers out there, but the percentage of cons/flippers is way higher than the good folks looking to pass along a car that they no longer need.
As a first-time buyer, I would look at certified preowned cars from reputable dealers (and that can include carmax and carvana). Make sure they have a full service history (carfax, etc) and check to see what comparable cars are selling for to make sure they're consistent with the market. Find something that will suit your use case, has as low miles as possible, and fits your budget.
Another option may be to look into a lease on something new. Essentially you're renting the car for 2-3 years for lower payments, but at the end you can walk away. This can help establish and build credit as well, but leases have mileage limits and depending on the dealer and lender, other potential pitfalls. You also have no equity built up in the car at the end of the lease, so like renting an apartment, you're walking out with nothing to show for it at the end.
My 2 cents.