Welcome to the forums Donut!
I think you should start to break demon altars, so you can get new ores, and make an arena for the twins, skeletron prime or the own destroyer.
And if you want early wings in hardmode, use the leaf wings, even though they got nerfed, but still, you dont have to worry about the fall damage if you have wings.
That is my tip!
Welcome, Donut! Welcome to the forums!
And tips? Well I got one. Build walls that separate between each biome you have on the surface (or underground). But not all biomes though, just the one you think is worth protecting, like the biome where your towns are or biome that you think has an admirable lanscape. That way, you can prevent them for being destroyed when the evil is unleashed, and you can also monitor and contain the evil easily.
Fight skeletron prime first because he is the easiest mech boss, and fight the twins last because they are the hardest mech boss. Also a tip on fighting the twins, kill retinazer first, which is the one with the red iris.