Only spend what you have in your bank account and even then don't go crazy. I've met tons of people that are older than I am that when they first got their credit card they thought they had $6000 of their own money to spend. I'm sure most of you know that this is completely wrong. Another thing to note is with these sign-up bonus offers on certain credit cards don't go out of your way to spend more than you usually do to reach them. This isn't Boy math or girl math. We're here to teach responsible spending so that you can work and use your money on what really matters. I have also come to know that there are some people who just aren't credit card people because they aren't able to control their spending. I would recommend that you don't opt into the credit card game until you are able to responsibly spend your money and become financially literate.
NEVER Carry a balance(If you have no other choice there are some ways to help this)
If you can don't cancel any credit cards that you have gotten(even the ones with annual fees) Always look for the ability to downgrade cards to a no annual fee one. An example of this is the Chase Sapphire Preferred ($95 AF) can be downgraded to a chase freedom unlimited ($0 AF). The reason for this is so that you keep your credit age and history. Once you cancel a credit card it gets rid of the entire history you have had with that card.
I'm probably missing a couple things just off the top of my head. Write down below what I'm missing.