my friend, I feel you. This was my situation almost exactly.
going into the swamp is the first big difficulty jump in the game, and I learned some hard lessons about it. the following are my lessons learned in order of importance.

-do not approach a swamp from the water. there are more mobs on the edges of biomes generally but more so for the swamp because of leaches. if you sail to a swamp and cant find a neighboring Black Forest or meadows then maybe find another. your goal is to make landing in a good place and put down a portal RIGHT AWAY. you will need to build a Karve. the raft simply isn't an option.
-It's really about learning how the mobs fight. this is just one of those things you need to experience for yourself to truly get. you can't just plow thru drauger with bronze gear so learning their movements is key. incidentally this is how I really got the roll dodge down.
-Use the large indestructible trees and crypt tops for building safe houses/portal huts. most mobs cant touch you there.
-because you are constantly wet in the swamp, the rested buff is MANDATORY.
-the hoe is your best friend. use it to make paths through deeper water to avoid leeches. this will also make roads to follow so it's not so easy to get lost.

there's more but others have touched on them and these listed here were the most impactful for me personally. happy hunting.