Elder is easy, just keep behind pillars and move when he makes roots spawn. No need to build workbench or ANYTHING to prepare to fight him. If the Elder isn't easy for you to beat with fire arrows, you're deff not ready for the Swamp alone.
Cook better food & get all bronze gear. You cannot rush other biomes if previous boss isn't easy-ish for you.
Just like people complaining about the deathsquitos, they are suppose to be easy, block with shield and hit once. If it still does big damage to you with shield block, go back to mountain and craft better gear.
Key is food & gear. Skills can be relatively low but if equipped properly, you shouldn't have problems.