No curses. Wiccan's don't have many rules, but the big one is don't harm. "Harm" however is up to interpretation. It could include love spells which toy with a persons free will, it could be eating meat, perhaps physically attacking someone, saying hurtful things about someone, or gossip. The quickest explanation is no curses, which seems to be a given in the Wiccan community.
What Wiccans can do is pretty much anything else. We can cast spells if we wish provided they don't harm someone. We can eat meat if the Wiccan in question doesn't see it as harmful. We can basically do whatever we want provided it does not contradict the Rede which acts as our code of conduct. If you have a list of things you want answered like "can Wiccans smoke" or "do Wiccans fast" I could be more helpful for you.