Wiccans have a simple code called the Wiccan Rede, which says, If it harms none, do as you will. This is similar to or at least tends to have the same outcome as the Christian dictum, Love thy neighbor as thyself. In other words, dont hurt people.
This sounds straightforward, but of course people disagree as to what harm and hurt may consist of. As an example, the Talibans in Afghanistan (and Pat Robertson in the U.S.), think that adulterous women should be stoned and not to do so constitutes harm to the community and the individuals concerned. However, Wiccans, being products of our society (including its Judeo/Christian heritage), generally have normal, middle-of-the-road, Western ideas of Harm and Good, and behave accordingly.
The other part of our rule, Do as you will, is not entirely simple either. The not-doing-harm, implicitly to oneself as well as others, means the Wiccan Rede is not an invitation to excess and self-indulgence. In actuality the motto is borrowed from ceremonial magic, where it means finding out what your true nature is and fulfilling that but not at the expense of other people. Its an invitation to self-development, self-expression and making the most of your talents and interests. It also involves responsibility, because you have to think about and decide matters of harm, and your true will, and then live with the consequences of however you choose to play them out.
As an aid in figuring out these matters of ethics, Wiccans also keep in mind the law of threefold return. By this we mean we expect to get back in kind what we put out, only magnified three times. Most of us dont take it literally, as a matter of cosmic bookkeeping, but as a reminder that we get along better if were kind more often than not. For those cases where the threefold return seems a little slow (as when our good deeds go unrewarded, and other people apparently get away with their bad deeds), we take comfort in the idea of karma, whereby what you do will catch up with you eventually. Even if you have to wait a lifetime or two.