During a year of typical condom use, 14 out of 100 women will become pregnant. During a year of perfect condom use, that number drops to 3 out of 100 women becoming pregnant.
To use condoms consistently and correctly:
Use a new condom each time you have sex.
Store condoms in a cool, dry place, out of direct sunlight.
Don't use a condom if it is damaged, discolored, deflated, brittle, or sticky from lube.
Check the expiration date before you use it.
Carefully open the condom package, being sure not to tear the condom.
Put it on the erect penis before you have intercourse.
When placing the condom on the penis, leave space at the tip for ejaculate (pinch an inch), and gently squeeze this tip as you unroll the condom all the way down the shaft.
Use water-based lubes.
If the condom breaks during sexual intercourse, withdraw the penis immediately and put on a new condom before resuming intercourse. Contact your health care provider to ask about emergency contraception
While the penis is still erect, withdraw it immediately after ejaculation: grasp the rim of the condom between the fingers and slowly pull out (with the condom still on) so that no semen is spilled.
I hope that helps.