There's not much I can add to Mollie's excellent post besides an addendum for the uncircumcised male baby. Both my birth-boys were left as-is and we didn't have any problems keeping them clean once we realized that they're meant to be self-cleaning. Most uncircumcised baby penises have "adhesions" which will go away as the baby grows, but which meanwhile keep the foreskin from retracting. The foreskin and the glans penis are mucus membranes in their natural states, so they will secrete a "cheesy" substance that will collect at the tip of the penis. Just tug the foreskin back as far as it will comfortably go, wipe off anything you see and pull the foreskin up again.
As the baby becomes a boy and begins to take his own baths, teach him to pull back his foreskin and clean inside that "willy pocket."
Side note: If you want to leave your boy uncircumcised, don't let your doctor bully you into it. Adhesions are normal and will usually go away completely by the time the boy is toilet-training age. The only medical reason to circumcise against your inclinations is strangulation, i.e. the foreskin is so tight that it's cutting off circulation to the penis. This is pretty rare.