To gain new skills in poe currency, you'll usually need to equip gems into sockets on your equipment. Any class can use any skill, but gems do have stat and level requirements. Gems can only be outfitted in slots of the same colour.

Support gems: All these gems modify supportable abilities when equipped at a connected socket (one with a line drawn to another socket). The service gem has to be harmonious with all the gem at the connected socket so as to get an effect. For instance, a service gem that affects projectiles won't do anything to a connected melee attack stone. Make sure your connected gems are compatible!

Equipped gems also level up as you make XP, getting ten percent of the base XP granted from monster kills. Thus you can certainly level gems by replaying areas that are a couple of degrees lower than your existing degree.

Every part of loot you get takes up varying amounts of space in your luggage compartment. To take as many potential things at the same time, you need to move items around and squeeze things into the allotted spaces. Even then, your luggage is likely to fill up quickly in the event that you pick up every single item you encounter.

The trick, then, is to buy poe chaos orbs ignore items that your character can't utilize or are of low price.