When applying for your first credit card, you'll have a high chance of being denied due to poor history or "thin credit file". Essentially, you'll need to prove you are good with credit to get credit. While a roundabout way to get credit, there are a few ways to get the balling rolling to establish credit.
The easiest step will be to get a "secured card". In short, you pay $500 bucks and in return you get a card that you can spend up to $500 bucks on. The idea here is that you can then use the credit card and pay off the bill on time, this will the be reported to the credit bureau to show responsible credit use. Why "secured"? If you don't pay, they have your $500 anyway so they'll never be left owed any money. Of course this also means they'll report bad history to the bureaus. The rule here will be: Once you have it, pay on time, always!
Now, you can try a slightly more creative way to get some sweet credit history. To do this, you'll want to get a trusted friend or family member to add you on their credit card account as an "authorized user". Once they do, a new card will arrive and they can immediately shred it. Why? Your goal here is, as long as they are a responsible user, they continue their good credit habits (rarely hit the credit limit, pay on time every month). As they do, the credit card will report their good history on your report too! I did this for some family members and while more than half of them are under 18 (yes, you can add an underage users on a credit card, with some credit cards having NO minimum age for an authorized user) they already have a strong credit history.
...of course, if they fail to pay or handle their credit card poorly, they take your score down too so choose carefully!
From here, using either option (or both), you'll quickly start build your credit score. The only step remaining will be to monitor & protect. To monitor your credit score, you can use a free service like Credit Karma (of course, free but you'll get email and in-app ads but it's either this or pay monthly). To protect your score, you'll want to enable a security or credit freeze on your report for each account. During COVID, credit companies were forced to make this free so you will not pay a dime, just google Experian, TransUnion, and Equifax plus "credit freeze" and you'll find the sign for each one. Make sure to skip past any paid "credit monitoring" services because they do nothing to protect and simply alert you of possible fraud. This would be equal to having an open door to your house but a security camera instead of simply locking your door in the first place.
Lastly, good credit history will build for your over time. Rules to keep in mind now is to always pay on time and stay under your limit by using no more than 30% of your credit limit with less usage being even better, and that you do NOT need to carry a balance to get good history. Always aim to pay your card off in full every month as the goal is to build credit, not get caught in their web and get tied down with ridiculous interest rate. If you can't pay for it in full when the bill comes, don't use your credit card.
Next time, (if wanted) I can do a write up on creating margin and building an emergency fund.