Swamp is where food and potions really start to be super important.

My best advice is search the swamps for food items. With upgraded food and poison resistance potions the swamp is a lot better.

Of course don't go there at night unless you want to make it more difficult.

The swamp key is obtained by killing the second boss. So you should have decent bronze gear. If you skipped bronze for iron you have to be a lot more careful.

Did you console in a swamp key or get one from another players world?