The pros are:
- You're not spending your money until the bill comes in
- If there is an issue (fraud, refund, stop-payment) then your money is not tied up; the bank's money is
- You can get cash-back for purchases which you were going to make anyways
The con is discipline, period.
Psychologically you need to be responsible enough to not fall for the classic advertised trap of:
Increase your purchasing power with a credit card.
If you wouldn't buy it in cash then do not buy it on a credit card, simple.
My personal habit has been to have one and only one credit card inside my wallet which I use for 100% of my purchases.
Yes, I too sign up for new CCs just for the bonuses. I shift my bills to those CCs until I've earned the bonus and then never use them again.
Do NOT sign up for a CC just because it advertises some great cash-back rate on something you purchase infrequently. CC companies employ the "divide-and-conquer" rule meaning that the more CCs you use then the more likely you are to overspend and that's how they conquer your money.
Do NOT add authorized users for the sake of adding an authorized user. If they aren't paying your bill regularly then their name should be nowhere near your card. My wife and I even maintain our own cards which we are responsible for.
When traveling, especially abroad, consider equipping yourself with 2 or 3 cards just in case one of them has an issue or is lost/stolen. However, remember to practice discipline!