There are several things you should know before you get a piercing, but, more specifically, these are things you absolutely should not do if you want to avoid infections and risks.

Do Not Do It Yourself!
You will not be in a sterile environment. And no, wiping things down with alcohol doesn't count. Piercing shops use chemicals that kill 99% of all diseases in 1 minute. Alcohol is merely a disinfectant, meaning it does not kill all pathogens. Sterility is absolutely vital when getting a piercing, as it greatly minimizes the chances of getting an infection, or even a disease!

Trained professionals know how deep to pierce, where to place it, how much it will swell, and all sorts of other things that you cannot be sure of. All of these things are very important in getting a safe and nice looking piercing. Your tools won't be clean. You do not have the equipment to sterilize the needle, the jewelry or the clamps that will be used. Again, alcohol isn't good enough!

Do Not Go To The Mall or Random Shop
There should be no question of having it done by some inexperienced salesperson who's waving a piercing gun at a kiosk in the center of a mall! Piercings done at the mall are done by a non-professional (some take a training seminar that lasts from 2 days to 2 weeks, and some just watch a video! Piercers apprentice for months.) with a piercing gun.

Reasons to avoid piercing with a gun:
Guns really cannot be properly sterilized, and even the tiniest droplets of blood from another person can infect you with HIV, hepatitis etc.
The punch through your skin could be very painful. The scarring is more likely to result. Scars can turn into thick purple ridges of skin alongside the piercing site that will never go away. Or you can end up with a piercing that is sunken into the skin.
Piercing guns place shorter pieces of jewelry into the hole that they make, and the jewelry is more likely to sink into the piercing. If the jewelry becomes lodged in the piercing site, you have yet another possibility of scarring and infection. A piece of jewelry that is too small can possibly interfere with the blood supply to the area.

Non-professional piercers do not know the risks associated with piercing, nor do they take the proper steps before piercing you to ensure everything is clean. They can't - the layout of a mall shop doesn't allow for sterilization.
Malls also do not offer appropriate aftercare. While shops differ on what they offer, the one thing all professionals agree on is to not use alcohols, which is exactly what most mall shops will give you. They may also give you antiseptic wash. Both will dry out your skin terribly and prolong the healing period.

Do Not Play With It
Besides keeping it clean, the best aftercare is to do nothing. Don't touch it, don't play with it, don't turn it. The less you mess with it, the faster it will heal and the happier it will be. Every time you move it, you are making that wound fresh again. Leave it alone and it will heal all by itself.

Do Not Change It
Because starter jewelry can be plain to look at, people are often tempted to change it right away. What they forget is that there are good reasons we use that jewelry in a fresh piercing. Jewelry that is colored or has jewels can't be properly sterilized, and you want sterile jewelry in a piercing that isn't yet healed. Jewels can also be bacteria traps -- when you're healing, lymph will come out (that's the crusty stuff around your piercing) and if you're wearing a jewel, it will stick to it, making it far harder to keep clean. Starter jewelry is plain for a reason - it's sterile and easy to keep clean. Make sure to leave it in for a minimum of 3 weeks; even longer is better.

Do Not Listen To Your Friends
Everyone is different, so what happens to one person may not happen to another. If you have any questions or concerns about your piercing, go talk to the piercer who did it. They are trained to recognize problems and can often take care of any issues it may be having. They can also help you change your jewelry, assist you with aftercare and sterilize your own jewelry.

Do Not use alcohol
That could sting if it gets too close to the new piercing and is far too harsh ur piercing. And removing the unattractive coloration isn't just an aesthetic issue. Iodine should be removed from the skin after the piercing is done to prevent any irritation.

Jewelry - Random Shop or Street - Do Not Buy It
Choosing a suitable Body Jewelry is very important.

Avoid Viral Infections
Viruses such as Hepatitis A, B, and C, and HIV can penetrate a piercing that has not healed. These viruses may be present in the blood, saliva, semen, sweat and vaginal secretions of infected persons. Until your piercing has healed avoid any other person's bodily fluids contacting your piercing.
Keep hair products, skin care products, and similar foreign substances away from your piercing during this period.
Initial redness, swelling and discharge are usually normal, but if it continue to appear it's probably some infection. Then you should visit your piercing artist or a doctor.  After you see that something is going wrong with your fresh pierced area you should visit your piercing artist and ask for help. In some cases probably the best choice is to visit a doctor.