General

God bless.

From @Traitor

If you need help in any of the steps below, feel free to PM me. [Note: Most things in this guide does not require NX, you just need patience]

Training, most people grind lower levels til you can PQ and PQ pretty much levels you fairly quickly to the major grinding phases at ~160. FM seems a little more empty now but there are a lot more shops around, especially in Scania. Since owls are now purchased through pot shops, you can easy pick some up and just search for the items you need[other that Perm NX items].

Basic training guide:
-Starting from level 1-10, you pretty much just job advance as usual.
-Once you're level 10, you can go to Golem Temple in Henesys in which you can level there until 25-30.
-Once you're level 25-30, you can move to Gold Beach. I would start on the left side map with the coconuts and work my way up to Shockwave Beach 1. I would stay here until around maybe level 50-55 or so.
-Starting at level 50, you can go LudiPQ. PQs are now all gathered in one place available by the Dimension Door in most towns. I would Ludi PQ until level 50. [If you do not wish to PQ the whole way, you can go to drakes at around level 55-60 and work your way to 70]
-Once you are 70, I would do Romeo and Juliet PQ and stop and grind at the stage with the Roids. This stage is the best for exp even grinding outside of PQ best optimized with a Phantom/Priest with HS and a Kanna for Kishin. Other Alternatives are Sahel 2 in Ariant. You can stay grinding in this PQ until 140-150, it's pretty much the fastest way to level IMO, unless you wanna try to grind in some maps in Magatia which is a bit slower.
-Once you hit 140 you can do a party for Dimension Invasion PQ if you can't solo it yourself, you can pretty much do your daily 10 PQs and then go grind at Mysterious Path 3 in Singapore. Once you reach 165, you can now enter Stronghold. Note:Honestly, I really don't recommend it unless you have friends to leech off of or unless you can do 1-3 hits. Otherwise, the exp isn't as great and you're better off doing your daily DIPQs. You can pretty much farm the gloves in DIPQ and sell in a shop for a couple mil apiece, I'm not sure where the price stands right now.

You can boss in-between for optimal experience. The default key is O in-game I believe for the boss tab so you can check the requirements there.

Items to think about having eventually for end game: (This may prove to be expensive, but I will post the affordable equips after]
-Chaos Root Abyss Set [Hat, Top, Bottom, Weapon]
-Tyrant [Glove, Shoes, Cape, Belt]
-Sweet Water [Glasses(Eye), Tattoo(Face)]
-Superior/Reinforced Gollux Set [Ring, Pendant, Belt, Earring] (if you use Tyrant Belt, you would have to use NX to purchase a pendant slot to equip 2 pendants to get the full set bonus]
-Rings [Since the Gollux Set takes up a ring slot and unique equips, you can pretty much get one of each Gollux RIng, if not Lightning God Ring for the best stats]
Note: This is the generally ideal set but by all means you do not need to chase this as this is VERY expensive.

Cheap but Efficient Equipment Guide:
The CRA set is a couple hundred mil apiece but there may be some pieces out there depending on class for a couple mil. If you cannot get this, you can try to buy the empress set for the bonus effect stats. Personally, I would say save your money and at around 140, you can grind at the higher leveled monsters in Leafre or the Pirates in Herb town. They drop the new level 130-140 set which gives a set bonus as well. If you take this process, you can save your money but slowly increase your damage. These level 130-140 sets are also tradeable so you don't need to purchase use SoK or pSoK to transfer them character to character. Next I would try to purchase cheap solid/reinforced gollux pendant/belt for small range increase. If you hunt bosses, easy bosses around be Zak/Horntail/Hilla/Magnus/Ranmaru in the easy/regular modes(you can do these twice daily, bring a friend if you must), I wouldn't attempt harder modes until you're geared and much stronger. The bosses drop accessories[Eye,Face,Ring,Earring,Badge, etc.] that also have set equips. If you find some Epic / Unique accessories, you may make a quick buck. Remember, though you won't be getting rich fast but patience is the key.

Scrolling:
-The scrolling system has been semi-replaced with the Spell Trace system which you collect a required amount of traces to use a scroll. How it works is you double click the Spell Trace in your etc tab or the Pink Hammer in your inventory window and place the item in there. You can then see how many traces is required per scroll. If you're poor, I recommend 70-100%ing your items, except for weapons which I always recommend at the very least 70%ing it.
-The enhancement system is semi-replaced by the Star Force system, this system takes effect after you finish scrolling an item. Once the item does not have any slots left, you can add additional stats by enhancing it with Star Force which is done by the Pink Hammer. I recommend Star Forcing all your equips until 10 stars because it is fairly cheap to do so. This will also increase your range by a pretty fair amount.

Potentials:
There a certain tiers for items to have potential which has 4 different ranks. I wouldn't really worry about potential items unless they are above level 75 which is the 3rd tier.

First Tier: 1-30, items will generally have lines in multiples of 1%. (2%, 3%, 4%)
Second Tier: 31-74, items will generally have lines in multiples of 2%. (4%,6%,9%)
Third Tier: 75-159, items will generally have lines in multiples of 3%. (6%,9%,12%)
Fourth Tier: 160+, this one is a little unique because the lines are 4% (7%, 10%, 13%)

How it works:
if your item is Rare, you will generally have the lowest multiple.
if your item is Epic, you will get the maximum landing at 2nd multiple.
if your item is Unique you will get the maximum landing at 3rd multiple.
if your item is Legendary you will get the maximum landing at highest multiple.

So for example, your Legendary item unlocks the potential to have the maximum % but you can land any of the %s below it, such as rare, epic, unique. So if you get VERY lucky, your lines would all be of one stat but don't be so sure to expect to get that easily. You will be spending many, many, packs of cubes. The best time to cube is during miracle time when nexon does a 2x-like event for cubing, increasing the chances of rank up. Again, I don't recommend cubing anything below the third tier.

Weapons and armors have different potentials. Weapons have additional stats such as att/matt where as armor is generally stat based. You can make cubes but farming the materials and leveling the skill level takes time. I would recommend picking up professions as soon as possible to start leveling it up. Sometimes when you make equipment, such as earrings, you can get epic/unique items which you can sell for a fair amount, meaning you can make money this way. When you mine mysterious rocks you also have a chance to find cubes(other way would be bossing)!

Nebulites:
You don't really get to see this much but people generally applies this to weapons. Select few rich players have acquired a lot of nebs for their armor as well.

How it works:
You can purchase a nebulite socket opener thing from the pot shop and apply it to your item. You can then apply your nebulite of choice depending what you have.

Weapon: I would put on a %boss or %pdr neb or % att neb for endgame. If you can't afford it, you can use an att neb or crit neb. Think wisely because removing a neb costs NX.
Armor: I always recommend %stat nebs but if you're poor, again you may choose to use simple +stat nebs

There are some useful but expensive skill nebs with skills such as Hyper Body for pants and Sharp Eyes for gloves meaning that regardless of class you can use both those skills but at a nerfed rate. The stats only apply to yourself however.

Souls for Weapons:
This is a newer system where you can even more stats to your weapons.

How it works:
You use a soul enchanter on your weapon, these drop from monsters and some bosses. Once your item is a soul weapon, you equip your weapon and apply the soul. If you do not have a soul, you would have to hunt bosses which drop soul shards. Collect 10 shards to trade for a random stat soul in which you can apply to your weapon. Some souls are attacks, some are summons.

I came back a few months back and I found this due to personal research/playing so I hope it helps. I don't know everything so I answer most things to the best of my ability.