You store the condom in your pockets/wallet. Where you keep a condom matters. In your wallet or pocket, it can get compromised because of the regular friction and warm temperature.
You used it beyond expiry date. Like every other thing, condoms have expiry date and they offer little or no protection after that.

You use your teeth/sharp object to open the wrapper.Your teeth can cause a tear in the condom. The packet should be opened with your bare fingers, You wear it after gen ital contact. The best thing to do is to wear your condom before any genital contact to protect you from other fluids like pre-cum (men) and vagina fluids.
You wear it too tight on your pen is. When you wear a condom, leave a small space for ejaculation and sperm collection at the tip. This will prevent leakage and rupture of the condom when you ejaculate..