First off, there is NO form of birth control that is 100% effective, except for abstinence.
Second, emergency contraception, such as the Ipill, Plan B, morning after pills, etc., are NOT as effective as a properly used condom or birth control pill/implant.
Use protection ALL the time and before any sexual contact. Do not reuse a condom. If it is put on wrong, throw it out.
The "pull-out" method is NOT a reliable form of birth control.
Hope it helps.
Learn to use protection as in a Condom. This not only prevents sperm from entering the vagina but prevents from sexually transmitted illnesses. For the girl this also means protection from getting urinary tract infections.
If the condom leaks or tears during sex, then there are emergency pills known as Plan B pills - sold under different brand names. These pills work best when taken within few hours of unprotected sex, though they can work if taken within 72 hours of sex. However with each passing hour effeciency diminishes.
Always remember that birth control pills [taken throughout the cycle] or taking Plan B pills - they are all hormonal pills. These have tons of side effects which range from mood swings, anxiety, depression, weight gain, period changes, heavy bleeding in a girl. So, choose an informed decision