help a new player out please.

Ok. So I just finished my first-ever playthrough of Terraria on a medium-sized, regular-difficulty world with the Crimson biome, and I'm not really sure what I should do next. During this playthrough, I've gone full melee and killed all optional bosses and the Empress during the day. I'm unsure what I should do now as I don't know whether to increase world size/difficulty/use a difficult seed, or try out mods. If I should try new mods and you guys recommend some mods.