The following is the recommended gear progression for every class.
RHD, or Random Hard Dungeon should be your starting point. Thse will be the same dungeons you've run through while leveling, however, every mob will be scaled up to level 50. Bosses are also guaranteed to drop level 50 gear, though it's not guaranteed you'll get the drop for your class.
While it's recommended you have full RHD gear before raiding, It's not all that necessary. If you have a decent raid group, 3 or 4 pieces should be plenty to get you through your first raid. However, if you intend to ru with pick up groups, having a full set is better as you're not always guaranteed to be paired up with people who can do well.
Tier 1 raids include Baphomet's Garden and PvE Arena. Each raid, like dungeons, has both a normal version and a hard version, and similarly, the hard versions will have better loot. However, as a beginner, it's recommended you start with the normal raids to get used to raiding, as well as gearing yourself up to take the harder hits that come with the hard versions of each raid boss.
Running Baphomet's Garden will drop a pants token, a shoes token, and a class specific weapon. PvE Arena will drop offhand weapons for knight (shield), ranger (quiver), and soulmaker (handle), gloves tokens, headgear tokens, and shirt tokens. Both raids drop accessories.
Tier 2 only includes Culvert of the Abyss. While this also has a normal version, it's recommended that you don't jump into this raid until you're comfortable with, and suitably geared up from the hard versions of the tier 1 raids. Most, if not all the bosses in CoA are several times harder than what you've probably experienced before in the other two raids, and require you to have at least some common knowledge on how to raid effectively, and will suitably punish you for making stupid mistakes. As with tier 1, start with normal mode first, and move onto hard.
Unlike tier 1 gear, you will find every accessory and armor piece inside each version of CoA. Culvert Band will drop the gloves. Golden Robberbug will drop the pants token. Mini Mongi will drop the helmet token. Aromine will drop the chest token. Ratmaster will drop the shoes token, and a random class main and/or offhand weapon. Accessories will drop from both bosses and mobs.
Having matching pieces of CoA gear will give you a set bonus increase to certain stats such as dodge, parry, haste, etc. depending on how many pieces of the set you have equipped. You can mix and match normal and hard versions of the set and still retain the set bonus, however, they must be of the same armor set. You can not mix a tank piece with a DPS piece and get both benefits for having two pieces of armor.
Between CoA and AoD, you can choose to participate in Colosseum. While primarily used for PvP situations, the colo gear can also be used inside raids, and despite not having the set bonus you would get from CoA gear, the stats are much better and will provide you with more offensive/defensive ability than if you were to have full CoA. This set rests in between CoA and AoD in terms of progression, and you can start making progress on obtaining the gear as early as level 10.
Tier 3 includes Abaddon of Despair, and like the previous raid, it continues to raise the difficulty, though by time you unlock it you should be fairly comfortable and familiar with what to expect from raiding. Unlike the other raids, however, the normal and hard versions of AoD swap some of the boss positions around, with two being exclusive to their respective difficulties. However, like CoA, all gear will drop from each version of the dungeon, and only the boss who drops the gear will be different.
Similar to CoA gear, having matching pieces of AoD gear will give you a set bonus. While initially the numbers may look smaller than what the CoA set is giving you, remember that CoA only gives you a % increase based on your current stats. AoD, on the other hand, will give you a flat increase regardless of what you had beforehand. It'll add up in the end!
Crafted gear info will be edited into this post later on.