This game is insane for how much there is to know. I often have six wiki pages up, have played for a couple thousand hours over two years, and I still didn't know this about Kaoms roots. I'm a fairly new player, and got into the game because I like the complexity. But, the complexity does not come with its own intuitiveness. There are so many things wrong with what this game doesn't show you, and how much outside knowledge is required.
For example, here's what you need to have just to start off with your first character:
1. Some sort of PoE passive planner
Because trying to figure out the passive tree on your own is going to gimp your character so goddamn fast without planning. Even then, you need to dive into other example builds to get an idea of where to go, or full-on "netdecking".
At the very least, you need to download the default set, because this game shits out more metric tons of useless junk than any other game I've ever witnessed. (Don't believe me? Hold down Alt and see how much you've been filtering.) Later on, you'll want to customize it with this highly complex and highly intimidating filter system. (To be fair, the FilterBlade team do a damn good job trying to make its system intuitive.)
3. Many many many different wiki tabs
Because the interactions with passives and gems are soooo full of holes. Did you know that traps are considered secondary damage and don't leech or are even considered your kill for mana/life benefits? Did you know Summon Skeletons and Chance to Ignite doesn't work, even though the gems show as linked and the effect is listed in the skill bar hover? Of course, the wiki knows: "The normal rules for burning apply, linking this gem to a skill that deals no fire damage is pointless"
4. Understanding the screwed up economy
Sure, there's a ton of different types of orbs, and some are easier to get than others. But, hey, let's say I used a ton of Chromatic Orbs, since I get those all the time, and need just a few more. Let me just go to the trader and see what the price is to get a few more. WHAT?! 4 Jeweler's Orbs for 1 Chromatic Orb? Are you fucking serious?!
Because there basically isn't an in-game trade system worth using within the game. Also, in order to even trade with players, you still need...
6. A guide on PoE trading etiquette
Yes, people who you're going to trade with expect you to already know exactly what to do. Use the poe.trade whisper, have the money ready, expect him to jump into your party, go to his hideout, etc.
7. Knowledge of item manipulation odds
After all, trying to link together a 4L was pretty easy, so going one more to 5L shouldn't be that hard. Right? Right?! Chromatic Orb just randomizes the colors to whatever I want, right? Huh, what do you mean it's linked to the attribute types? How do I get GGGB on these ES boots?
Do you want to poe buy currency? If you do, you can visit U4GM to have more guides and methods about this.