A handy-dandy Wikihow article on how to make a horcrux, for all you aspiring Dark witches and wizards out there!
An example of an object you could use.
1. Become an extremely powerful witch or wizard. This will take years of study and sacrifice which lie beyond the scope of a WikiHow article. As a general guide you should not attempt to create a horcrux until you can cast non-verbal killing curses.
2. Locate an object of extreme significance to you. An emotional attachment to the object will aid the process and make it easier on your body and soul.
3. Bathe in the Water of Sorrows and eat 1 cup of paste made from the Herb of Undeath no sooner than 12 hours before committing the principal act of the ritual.
4. Cast the preliminary incantation in the presence of your object. Bring your wand from hanging medial at your side to in front of your heart at approximately 45 degrees from your waist. At this point you should flick the wand in a circular fashion 146 degrees and then whip it outwards to the full extension of your limb. During this last movement issue the following command: "Voces fallacis amicae"
5. Perform an act of unspeakable evil while carrying the object you wish to turn into a horcrux. Murder is dirty but very effective in this regard.
6. Within 15 minutes of performing the act, clutch the object you wish to turn into a horcrux with both hands and yell the following incantation: "Diabolus fecit, ut id facerem!"
7. You will lose consciousness. This is a normal part of the process. When you have awoken the object in your hands will be a horcrux. You will feel very different (some have described the feeling as if you are "half empty") and will have an almost motherly affection to the object.
8. Cast protective spells on and around the horcrux, and do not tell anyone of its existence. You must eliminate anyone that finds out.
Although you should choose objects which are significant to you, be careful not to choose objects that can be linked to you with relative ease. This will generally send hordes of jealous followers or irritating enemies out to destroy your horcrux, leaving you half a soul closer to death.
Don't ask your potions master about the creation of horcruxes, as it may undo all of your plans at a later date when he feels sympathy for a boy whose parents you killed a decade earlier. It is easier to figure out the general process through this wikiHow article, through books in your school library (please remember to wear an Invisibility Cloak while browsing to avoid attracting attention), or ask general advice from the Dark Lord himself (avoid seeming too curious, or he may see you as a threat and set out to destroy your horcruxes).
Don't make your horcrux your pet snake. Remember, driving somone's parents to insanity MAY make them want to destroy you.
Do not attempt to split your soul into seven pieces. It sounds very fashionable but will turn you into a psychopathic maniac, assuming you are not one already. (Note: If you are a psychopathic maniac, it may be simpler to avoid the process all together, as it will simply cause you to appear more unhinged and cause man to avoid you).
When a teenage wizard comes to challenge you without a weapon in the midst of an epic battle, DO NOT attempt to kill him with the same curse which has already backfired on three previous occasions. He probably knows something that you don't.
Don't even bother trying to find the Deathly Hallows. Honestly, just don't.
While a teenage wizard is attempting to make an epic fight-to-the-death speech, realize that you do not need to listen to him. It would be much simpler to just perform the Avada Kedavra (Killing) Curse on the spot (or at least use the Cruciatus Curse.)But also remember warning #2 just in case
Do not leave behind any memories people may have that your old professor could use to figure out your plan and annihilate your horcruxes