It looks like you're playing melee based on the Beetle Armour? If you're not playing melee, I'm not sure what would be best as I don't often play ranged or magic.
For the early waves, use a weapon that can hit multiple targets. You'll want to pick off the weak enemies quickly. Vampire Knives can do this, but your arena has a good setup for healing, so you might not need them. Alternatively, use the North Pole, aiming upwards at a slight angle away from your character. You want the snowflakes to rain down on the enemies. The Wiki page on
North Pole has a GIF demonstrating its usage. If you get a Flairon, aim horizontally across from your character. The bubbles produced by the flail home on enemies. That is, don't target the enemies with the flail itself.
In the later waves, when Pumpking starts spawning, switch to Terra Blade or Influx Waver. Ignore the other enemies unless there are no Pumpkings on the screen. Leave the weaker enemies and Mourning Wood for your summons and traps to pick off. Pumpking gives the most points for advancing to the next wave, so you'll want to focus on Pumpking.
In your accessories, swap out the Mana Cuffs, Mana Flower and Ninja Gear for something to help with melee. (You might already be doing this, but changed for the screenshots?) You can swap them for the Star Veil and Ankh Shield.