Swamp is probably the trickiest biome to properly scout out. Finding a good one with multiple crypts can take time, so you will need to upgrade your boat. You won't die at sea as the sea serpents can be outrun easily with a tailwind. Your main threat comes from deathsquitoes if you stray too close to a Plains biome.

Get out exploring by sea; what you are looking for is a swamp biome with plenty of width - don't waste your time with long, narrow swamp stretches that you often see bordering other biomes. You may not see the crypts from the sea but if you can setup a forward base in a nearby meadow and build a portal to your main base then you are set.

As far as tackling the swamps themselves - i recommend a fully upgraded bronze mace to tackle the numerous skeletons and slimes, and any slashing/piercing weapons to deal with the draugr. Avoid any 1 star or 2 star units for now, steer clear of any spawners, run like hell if you trigger an Abomination spawn and beware the wraiths at night. Once you get into some iron armour the swamps become a lot easier and even eerily quiet at times.