[i'll go with a protection spell, but you can use this for anything, just visualize a different situation] get a necklace/charm/whatever you wish to enchant, first cleanse it [two easiest methods is place it in sea salt water or pass it through sage smudge] this will wash away any energy that might be clinging to it [everything you touch will have a small amount of your energy left behind. if 50 people pick up an object, there will be 50 different types of energy on it, so it's wise to cleanse all your tools for a blank slate]
hold the item in your hands, visualize/feel positive energy [white/silver/gold light. use what works for you. you can also personalize the colour depending on the energy, like pink light for love or green light for luck] entering your body [i typically feel it in my back/shoulders] traveling down your arms and pooling into the object in your hands [you should feel a warmth]
if you have a protection chant, say it and pass it through some protection incense [i typically use cinnamon incense or dragons blood. cinnamons my go to choice for all spells] if you don't have a protection chant, you could say a pray to your deities for protection.
if possible, leave it on your altar overnight to be blessed, or leave it in the windowsill under the moonlight.
you can begin wearing/carrying the charm the next day and it can last for a while, but i usually cast protection spells once a month [i just hold my pentacle necklace and say a protection chant] that way it stays strong.