"Business meeting"
4. Go With Generics
You know those people that dress for murder? Those people are probably already in jail right now, so lets completely disregard them. One of the first things you can before you plan to rob a store or murder someone is, make sure that none of your tools or possessions can link you to the crime.
When collecting evidence, forensic scientists classify evidence as either individualized evidence or class evidence. Individualized evidence directly links a specific person to a crime while class evidences only narrows down the possible suspects to a specific group or "class" of people. Wouldn't it be better if any evidence found in the crime scene can only link people with Nike shoes to the crime scene to opposed to people with hand-crafted shoes made out of extremely rare material only found from a specific region of the world?
If you're a horse, then you're on your own.
When purchasing clothing and tools to commit a crime, it's generally better to use 'new' and extremely common clothing and tools in order to increase the possible suspects of a crime, therefore reducing the chance of being caught red-handed the instant you leave the crime scene. Using 'new' generic items also assists your cause because any scuff marks on the "item" can make that item individualized evidence. For example, if you have a giant cut in the sole of your left shoe, your shoe print will mark out that special cut in extreme detail for your criminal investigators.
3. Wearing Gloves Goes A Long Way
Wearing gloves isn't just for those awesome computer hitmen that take on high-profile targets such as the ambassador of Spain or the president of the world. Wearing gloves while committing a crime can easily help reduce a large amount of evidence that could possibly link you to the crime scene. If your crime involved a gun, gloves can easily remove fingerprint and gunpowder residue evidence from the question.
Considering that your fingers are basically self-replenishing stamps that say "Hey! <your name here> was here!" to the judge/jury in court, you should avoid leaving fingerprints anywhere whenever possible. Thick gloves can easily erase the entire problem and let you escape the crime scene like some type of professional criminal with expensive leather gloves. (Any gloves you use should also be, generic. Also, using thick latex gloves is the way to go. Leather can sometimes leave its own "fingerprint" that can possibly be linked together later if the glove is recovered later.)
Pictured: You?
Gunpowder residue is one of the results of firing a gun and it can be used to determine if you've fired a gun recently. If you were wearing gloves while shooting bullets blankly into the roof to scare people, your hands would be as clean as cotton. (Of course, you would be scarred for life after taking peoples' lives for the sake of getting away. But good job anyways.)
Wearing hairnets help too. Their easily disposable, cheap, generic, and prevent your hair from entering the crime scene.
2. Commit The Crime Towards A Complete Stranger
Most crimes committed are usually towards people the criminal already knows. In fact, the first people the police will question are usually relatives and friends. However, if the victim has had zero connection to the suspect previously, it's almost impossible to determine a motive or even suspect you of the crime unless evidence directly points at you.
"This suitcase full of human organs isn't going to help"
Better yet, try to commit the crime far enough from your home town to not be suspected but close enough to get home without arising too much suspicion. This way, unless the police are tipped off or find evidence of you at the crime scene, they won't have a chance of finding you out of the billions of people on earth. Chances are, the police will only investigate friends, family, neighbors, and fellow-townsmen unless some mysterious evidence points otherwise.
1. Don't just hide your appearance, change your appearance
We've all see those people in the movies that slip on ski masks and run into a bank guns blazing. While you can technically attempt to hide your appearance, you can easily deceive people into a false sense of victory of identifying you. For example, you could apply temporary tattoos, removable piercings, wigs, and even false scars. Most detectives look for "individual" characteristics when questioning eyewitnesses and checking security cameras. If 90% of the characteristics are actually fake, what's the chance of directly linking you to the crime? (Unless you keep said piercings, wigs, items in a box labelled "stuff for crimes" in your closet)
And that's why you need a butterfly tattoo.
Extra
Knife made out of ice?
Forensic science has long investigated the most common weapons of blunt objects, guns, and knives so you can cross those out if you plan to commit the most perfect crime in history. Here's a suggestion, a ice knife. That's right. A knife made purely out of solid water. If it's sharp and sturdy enough, you can technically murder someone and get away with only a small puddle and wet hands.
Although, they don't make out as very intimidating weapons.