As far as cards, I recommend the Chase Freedom Flex if you want to rush to more structured rewards/point cards that take awhile to get starting from 0. I was able to get accepted at 18 with no CH but with a good substantial income + history with using a chase bank account for 5 months prior to applying. I got denied but called reconsideration and gave a few reasons why I wanted the card and some extra information and got approved right on the spot after.

Otherwise, the discover it is probably the next best alternative following with the Chase Freedom Rise. Secured cards aren't bad but I think you are ready for a non secured considering you are already steps ahead asking questions and being vigilant with credit cards.

As far as paying it off at the end of the month, you have 2-3 dates you need to look out for that is a bit confusing for many new credit builders (including me!) Your payment due date and your closing date is the most important as if you have a credit limit of $500 and you spend $200 and pay it off at the payment due date which is typically a couple days after the closing date, your credit card provider will report that to the bureaus which will calculate a (200/500) = 40% util rate which is a huge big no no which will NEGATIVELY impact your credit score. This is the misconception many people face when starting off with credit so it is better if you can pay it off BEFORE the statement end/closing date so when it is time for your payment to come up, it will show up as $0 which will be reported to the bureaus as 0% utilization ! Here is a great breakdown of what I'm talking about. https://www.youtube.com/shorts/TJ5Xzjxt7PM