For armor, try to get Turtle Armor. For accessories, some wings and damage boosters would be nice, also something that allows you to move quickly.
For weapons, I could recommend some of them:
- Death Sickle (it can shoot through walls, so it can be effective with a good arena)
- Terra Blade (a bit hard to get now, but it deals huge damage to it and it's pretty early on)
- Light Discs/Bananarangs (the allow you to deal constant damage, also use their ricochet ability)
- Fetid Baghnakhs (with a good arena and defensive stuff, you can kill in it seconds)
- Any good yo-yo with the Yoyo Bag (I've used yoyo's once against Plantera, they worked pretty well, but you need to watch out in the second phase)
- Spears that shoot through walls might be useful
For weapons, I could recommend some of them:
- Death Sickle (it can shoot through walls, so it can be effective with a good arena)
- Terra Blade (a bit hard to get now, but it deals huge damage to it and it's pretty early on)
- Light Discs/Bananarangs (the allow you to deal constant damage, also use their ricochet ability)
- Fetid Baghnakhs (with a good arena and defensive stuff, you can kill in it seconds)
- Any good yo-yo with the Yoyo Bag (I've used yoyo's once against Plantera, they worked pretty well, but you need to watch out in the second phase)
- Spears that shoot through walls might be useful