Terraria – How to increase the ranged damage-per-second

Personally, my loadout is as follows:

• Obsidian Shield
• Ranger Emblem
• Demon Wings
• Spectre Boots
• Philosophers Stone

I reforged my items to all have at least +3 defense each. Ranged damage might also be good. My main weapon at the time was a clockwork assault rifle equipped with either crystal or cursed bullets. The splash from crystal and the afterburn from cursed work rather well against bosses.

Preparing for battle:

• Set your spawn point to a bed in the Nurse's room, with an extremely easy exit out back into battle.
• Obtain several of every buff potion that may have even the most minor advantage in battle.
• Go to a relatively flat location outside your town, just far enough that monsters spawn, but not too far to where if you used your magic mirror that the boss would despawn.
• Wait at this location until the 'night music' starts. As soon as the music changes, you can summon bosses.
• Just before or immediately after summoning the boss, press 'B' to drink all your buff potions simultaneously.

During battle:

• If you are missing more than 100 health and you can drink a potion, do it immediately. The health potion cooldown is quite painful, and restoring yourself to full health is better than waiting for the cooldown to wear off when you're at low health.
• If any buff potions wear off, don't hesitate to press 'B' again. Potions are rather expendable, so wasting a couple potions is much better than risking dying and losing the boss battle.
• Use the gravitation potion to your advantage. It is much faster and more responsive than your wings, and does not have a limit to how high you can go. Fighting in the air is much easier than fighting on the ground, as you have 360 degrees of maneuverability.
• If you are stuck with low health and potion sickness, use your magic mirror to head back directly to the Nurse to heal up. You only have a few seconds to do this before the boss catches up to you, so be prepared to heal and immediately jump back into battle. Be sure to take the battle away from your town if the boss does catch up to you.

These are the strategies I used to defeat the bosses, hopefully they work for you as well!

It sounds like you have the right idea, but here's some tips or suggestions. Buff potions definitely help, and also you will want to make sure you are using the Greater Health Potions, not the lesser ones of course.

If you haven't done so already, I suggest you try making a very long bridge. It doesn't have to be completely flat but at least enough that it's very easily traverse-able and you won't get stuck somewhere by accident or fall into lava. You'll want to focus more on the battle than trying to get around down there.

My weapon of choice for this battle would be one of the flails (Or any big Sword such as Night's Edge) for the numerous mini enemies attached to the wall. Flails take them out easily and quite efficiently since you can hit almost all of them at once. Once those are all done for, this is when switching to the minishark is a good idea. It puts out lots of damage very quickly, obviously, plus the bonus ability to save ammo every-time you shoot it. If you have the Goblin Tinkerer I suggest you put some money in reforging weapons for better stats, not necessary but makes a very noticeable impact when you get a good one.

As for your accessories, you might want rocket/specter boots to get around easier; a cobalt/obsidian shield so you aren't knocked around or into lava, and also in case there any exposed hellstone you could accidentally walk onto; and a Band of Regeneration to quickly recover lost HP. The other two are up to your preference really. I would also suggest reforging these to try and get the Warding prefix (+4 defense). Again not necessary but it will help tremendously in the long run. Especially since having 5 warding accessories means +20 defense.

You can also try to focus on magic items to defeat it. A Vilethorn also makes quick work of the smaller enemies while a space gun (with full meteor armor) will constantly damage the actual Wall without ever using mana. A Demon Scythe is definitely my favorite weapon to use against it though. It will hit everything it passes through, and while it's "charging up", the boss can be directly over it getting hit 3-5 times guaranteed. The only problem is how hard is can sometimes be to find.

If you do decide to use magic items make sure you have a full 200 Max Mana and some Mana potions as well. Restoration potions can also help here as they give back both mana and HP but will give the "Potion Sickness" debuff on use, unlike regular Mana potions. You can also get a Mana Flower to equip. This will automatically use mana potions for you so that you won't have to worry about how much mana you currently have.

Once you do manage to defeat it the first time, beating it again will just get easier since you will have access to higher tier items.