Baptized minimally, communion plausibly. Note that you will have to get a sit-down (plural) with the priest anyway, regardless of your religious background.
Probably some group "events", having your face seen on a sunday morning and not claiming to belief in Cthulhu should do you fine already.
You could have already been validly baptized (say you are a Protestant or an Orthodox Christian), in such case it usually comes down to local practice and the strictness of adherence to the doctrine by the particular priest.
If you have not yet been baptized, then you can still get married in a Catholic Church, but it will not be a sacrament (i.e. it would amount to a blessing). Either way a special dispensation is required from the Bishop of the Bishopric in question. The issue of indissolubility of such a marriage is more complicated though.