Serial Killer
Serial killing can be a very rewarding profession. The murders, the axes, the bodies... And to be able to go home at night with the feeling a job well done. There are two types of serial killers - regular, and supernatural. Each has its own benefits, and are described below.
Regular
If you're going to be a "classic" serial killer, you can elect to go for either quantity (as many victims as possible), or quality (only fat transvestites by the name of Harold). You're also going to need to get some sort of schtick: zodiac signs, dressing like a clown, claiming you're a vampire, eating your victims, constructing a hotel of death, hearing voices from your neighbors dog, and so on. Remember: Be original. There are hundreds of serial killers out there claiming they're the Angel of Death, but very few claiming to be Andy Kaufman with an axe.

Once you've started murdering countless innocents, you may notice that you now have the small problem of bodies. But worry not! The crawlspace is an excellent place to dispose of your victims. Other good dumping grounds include: the nearby river, garbage bins, shallow graves, your specially bred flesh-eating pigs, and the homes of the parents of the victim. If you wish, you may choose to simply send pieces of the victims to the parents/loved ones. It is highly understandable if you want to keep some of the victim for yourself. They also go well with a nice kiyante sauce and some fauva beans.

Be sure to play mind games with the police who track you. One good idea is to send letters to the nearby newspaper taunting the lead detective, and then leave a series of clues to test their puny intellect. These can be anything ranging from astrological signs, nursery rhymes written in blood, to notes carved into your victims. Rest assured that they'll never figure it out, however, as their brains are too puny and yours too superior.

Supernatural

Many people opt instead to become a supernatural serial killer. This is a popular choice due to the near immortality and many sequels that comes with the job. But how do you attain this?

A few possibilities include:

Pact with the devil.
Get sentenced to the electric chair.
Get burned in the furnace where you killed all the children.
Have a metal rod shoved through your heart which then gets hit by lightning.
Wear the mystic amulet while you are gunned down in a toy store.
Make a deal with the creepy voodoo woman to avenge the death of your child.
Drown in the river because your Camp Counselors are too busy having sex, have your mom kill the bastards, and then arise in the sequel.

Once you become immortal, you will then need to get some props. These are as important as the classic serial killers "schtick", and should not be taken lightly. You'll be stuck with it for sequels to come.

Some possibilites include:

Hockey mask
Glove with knives
Big frikkin' knife
Hangman's Noose
Chainsaw
Puzzle box
Hook for a Hand
William Shatner Mask with White Spray Paint
Ability to appear in a mirror after your name is repeated five times
Lucrative movie deals

Whichever method you choose, just make sure it's the right one for you. Good hunting.