Reality check
Even if you are using other forms of birth control like the Pill, the Shot and the Patch, which are effective at preventing pregnancy, the only way to protect yourself against HIV and other STDs is to use a condom every time you have sex. Other than not having sex at all, condoms are the only method that protects against BOTH pregnancy and STDs, but they don't work unless you use them correctly and consistently every time you have sex.

Decisions, decisions
Condoms come in lots of colors and textures but only two things matter when choosing a brand: condoms should be made of latex or polyurethane (plastic) (which are way more reliable than animal tissue condoms) and they should fit snugly. Yes, they do come in different lengths, widths and thicknesses. Also, while male condoms are more popular, the female condom, which is inserted into the vagina, is also an option.

Making the purchase
You can buy condoms in lots of places: drugstores, grocery stores, convenience stores, dispensers in bathrooms and so on. There are also online retailers, including specialty condom sites as well as online drug stores and groceries that can mail them to you. Many HIV testing centers and health clinics provide condoms as well.

Many people feel nervous about going to the store to buy condoms, especially the first time. They may worry about what the cashier or others in the store might say or think. But remember lots of people buy condoms every day and the only thing you can really tell about a person buying condoms is that they are making a smart decision.

Inspection
Condom packages show an expiration date. If a condom is past the date, is ripped, or looks dry, brittle, stiff or sticky, it shouldn't be used. Keeping a few spares on hand is a good idea in case one rips while being opened or put on.

Handling
Condoms should be kept in a cool, dry place to prevent breakage or leakage. To open, the package should be torn gently on the side (not with teeth or scissors, which could tear the condom itself) and pulled out slowly.

Choosing the right lubricant
Using a pre-lubricated condom, or applying a small amount of water-based lubricant - inside and outside the condom can help prevent rips. Oil-based lubricants (for example petroleum jellies, body lotions, mineral or vegetable oils) should not be used with latex condoms because they can cause the latex to break down, reducing or eliminating the condom's effectiveness.

Putting a condom on correctlyThe condom should be put on before intercourse begins. Pre-cum can contain semen and STDs (including HIV) so you need to wear a condom the whole time. The rolled condom should be placed over the head of the penis after it is hard and erect, leaving a half-inch of space at the tip to collect semen. (Pinching the air out of the tip with thumb and forefinger can help to prevent breakage.) Next, the condom should be unrolled down the entire length of the penis until it reaches the base. Be sure to smooth out any air bubbles along the way. The condom should fit snugly so that it won't slide off during intercourse. If you start to put on a condom inside-out, don't use it - throw it away. You'll know it's inside out because it won't roll down the length of the penis easily. If the condom rips at any time, start over.

Removing a condom
Immediately after ejaculation, the penis should be slowly withdrawn before it loses its erection. The base of the condom should be held against the penis to avoid slippage or spilling any semen as it's withdrawn. The condom should be wrapped in tissue and thrown away in the garbage (not in the toilet as it may clog).

Protecting yourself from HIV during oral sex
According to the Centers for Disease Control and Prevention (CDC), it is possible for either partner to get HIV while giving or receiving oral sex. If the person performing oral sex is HIV positive, blood from their mouth may enter the body of the person receiving oral sex through the lining of the urethra (the opening at the tip of the penis); the lining of the vagina or cervix; the lining of the anus; or directly into the body through small cuts or open sores. If the person receiving oral sex is HIV positive, their blood, semen (***), pre-seminal fluid (pre-cum) or vaginal fluid may also enter the body of the person performing oral sex (through the mouth).

The CDC recommends you use an unlubricated latex or polyurethane (plastic) condom for oral sex on a penis. For oral sex on a vagina or anus, the CDC says to use a latex barrier (such as a natural rubber latex sheet, a dental dam or a cut-open condom that makes a square) between your mouth and your partner's genitals. A latex barrier such as a dental dam reduces the risk of blood or vaginal fluids entering your mouth. Plastic food wrap also can be used as a barrier.