What stuff should I do before Hardmode?

[TheForkG]

I started my playthrough only 2 days ago and I'm already at the WoF stage, I don't know what to do before hardmode but I feel like I haven't done enough stuff in pre-hardmode.
I've already killed all the other bosses, have molten armour and the night's edge, defeated the goblins, and got a few houses set up for NPCs.

 

[Stellar Mastodon 267]

Prep all arenas you will ever need and fight the OOA.

 

[TheForkG]

Prep all arenas you will ever need and fight the OOA.

I do need to make my arenas for mechs, ocram, plantera and duke
Sadly don't have the OOA in my version

 

[MechaDasÜberGoober]

Make sure you set up a cavern farm!
It's much easier to do it in pre-hardmode when you have all of the time, and the enemies are weak.
It'll be really handy in Hardmode.

 

[Impostor]

Make a Jungle Arena. Trust me, You don't want to make one with HM Jungle Enemies attacking you while building it

 

[Stellar Mastodon 267]

Sadly don't have the OOA in my version

What version are you playing that you don’t have the OOA?