Root helm gives poison resist making the blobs and other stuff like it trivial. So if you make any root armor i'd do that piece first.

Mace works on the majority of swamp biome monsters so until you have a frostner that will be your best go to weapon for most things. Abominations i'd suggest keeping your distance from early on and taking out with fire arrows. If you do melee them a slashing weapon is best, i honestly like going after them with daggers/knives.

Speed is often more important than total armor here so i recommend fully upgraded troll armor over bronze/iron armors.

Start making meads. Poison resist meads in particular if your not using a root helm. Stamina because your always wet in the swamp and stamina recovery sucks. Health for random oh **** moments.

Use the stagbreaker to kill things through walls in the crypts to stay safer.

Make some frost mead and once you have the iron pick axe try doing a little mountain exploration. You can find buried silver before killing bonemass by spotting it sticking out of the ground or using the stagbreaker to pound the ground and look for "too hard" messages like it bounced off something. If you can build a frostner you can tear the swamp and bone mass apart.

If you fight bonemass prior to getting a frostner and youre finding him too hard build yourself a treehouse near his spawner with a portal to base and use it to plink him with frost arrows until hes dead.