How do you properly put a condom on?

Here are the basics:: If the condom doesn't have a reservoir tip, leave a little room between the end of the penis and the tip of the condom. Roll the condom down over the erect penis. If you want to use a lubricant, make sure it's one that works with condoms - NO Vaseline which can erode the condom! After ejaculation, hold the condom at the base of the penis to prevent it from slipping off. Look up Plan B just in case