Enchantment is easy. The only thing anyone really needs to enchant an object is intent. In many ways, an enchantment is like a Thought Form that has been tied to an object. If you can visualize the idea in your mind and pour the energy of that idea into the object, you have enchanted it. Anything else you use to focus your energy to the desired result is just window decoration. In other words, if it helps to “sell” the idea, use it.
Just about any object can be enchanted. You are simply empowering it toward a certain goal. You can construct a charm using items that are symbolic of your goal or you can inscribe symbols into your charm such as runes or some other magic alphabet. The kinds of enchantment you can perform are limited only to your imagination.
I would refrain from using an edible enchantment however. It doesn't work like a regular charm you might give away. There's more room for trouble, and that trouble is harder to fix. If you enchant a necklace for instance, and something goes wrong, you still have the necklace and can destroy it or find some other way of disenchanting it. If you use food or drink in an enchantment, it's gone and can't be removed from the person affected. That's a fairly permanent enchantment.
This is one of the reasons most texts advise against love potions –you may lose interest or the subject may become too ardent. There's really no way to change a spell if the spell has been eaten. You end up having to work from scratch on a new spell and since it is new, there's no way of knowing if it will counter the first perfectly or just alter it. If you insist upon using edible enchantments, one of the few ways I can think of to reverse it later is if you had the presence of mind to gather whatever was left of it for future use. It would then be easier to attune the counterspell to the previous spell. Otherwise, it would really be hit or miss if you wanted to remove it.
Also, since it's not really a good idea to have enchanted objects lying about after their purpose has been met, it’s a good idea to work in a time limit. You can set this to a moon phase, a season, or the physical age of the subject you intend to be affected by the enchantment. If you need the object to remain charged, and you can periodically get it back into your possession, you can set it to wind down at a certain time and recharge it when you can.
There are a couple factors in how long an enchantment will last by itself. It depends most on two factors –your ability or power and your intent. If you have a strong ability to enchant objects, then the enchantment will naturally last longer. If you intend for the enchantment to last a long time and you have strong ability, the enchantment could last quite a while before fading away on its own. The length of the charge also depends upon the properties of the charm. Charms made of or containing organic substances (wood, herbs, bone, sinew) are not going to hold a charge as well as a metal or stone charm. This is because organic compounds are design to decay and so any spell based upon them will also decay.
There are some dangers in letting an enchantment wind down on its own without setting time parameters. If you just set it to fulfill its purpose and then just go kaput, it might become active again on its own. For instance, if someone with ability accidentally came into contact with it or if it interacted with other charms, it could regain its charge, and worse in the case of charm interaction, it could change or be changed by other active charms. There's nothing worse than a rogue enchantment. You never know what it might do.
When creating an enchantment, it is good to use items associated with the goal of the spell. If you intended to perform a love spell for instance, you would use things associated with love or beauty. This might be fruit (or the flowers, seeds, or wood of a fruit tree), flowers (esp. roses), mirrors, stones (notably amethyst or rose quartz) or something you personally identify with love. It is also possible to enchant a living plant (if the intended target likes and is good with plants), tying the living energy of the plant to the enchantment. This is good symbolism for any spell designed for the growth of something, whether it is love or prosperity or fertility. Of course, if the plant dies, well I'd take that as an omen and not try anything further. You might also enchant a place, but if you are not sure of your abilities, I’d avoid this final form of enchantment. With the ambient energies present in or moving through any area, there would be too much opportunity for the spell to run amok.
Whatever form your enchantment takes, it should be something that the person will want to keep close, either in their home or on their person, but which no one else will come into contact with on a regular basis. The best enchantment will be in the form of a gift freely accepted. Of course, you can make secret enchantments and hide them in a person's home, but that tends to get messy and will eventually (if not immediately) make you feel like a jerk or worse. Such things almost always end badly. It’s better to be up front and honest in all your dealings, magical or otherwise.