It's worth adding that imbuments are one of the most important things to have in Tibia these days. If you can afford it and unlocked the ability to do the powerful imbuements you always want to go for them as they are much better than weaker versions (capacity can be done at level 2 to save some money).
Depending on your vocation, how many slots your item have you will usually use:
For weapons/ wands: Critical Strike, Mana Leech and Life Leech.
Helmets: mana leech and skill boosts.
Armors: life leech and elemental protection.
Shields: elemental protections.
Backpack: capacity
Boots: speed or paralyse removal.