For first time players! Read, it will help :) - Gear/Gems/Refinement/Astrals

Also make sure you check out this thread for some other useful stuff.

Primary Equipment

First thing, get your enchantments to MAX as quickly as possible! Every 9 levels of enchantment gives you *roughly* a 100% boost to the base def/atk of a piece of equipment. Running around with partially enchanted gear makes you a good deal weaker than you should be! Save your L9 enchantment stones though :p Generally speaking I try to keep my enchantment success rate at around 50-60% until it gets to the point that it costs many hundreds of thousands of gold per enchantment. It's cheaper failing once or twice than buying the stones from the guild shop.

Getting the right equipment is key to getting anything done, if you are a low level it's tempting to look at the L30/40 sets and want to get crystaloids for them.

This is pointless and actually makes you weaker. This is especially pointless since one piece of the L40 set requires 80 L3 crystaloids and the L50 set requires 200! apiece. You will be L70 before you get enough crystaloids to make the L50 set.

The L20 set is the one exception, it is possible to get this set and it's useful. I wore the full set till I was L35.


In the Arena Shop you can spend insignia's for items. These sets are L35/L45/L55. (you will hit 35 far faster than you realize) So start saving your insignia's.
Getting Insignia's
Arena - 15 for a win, 5 for a loss, you can do 30 a day.
Battlegrounds - 30 if you lose, 80 if you win, you can do two a day.
Guild Battle - 400+ if we lose, 700+ if we win. (M/W/F)

For those of you wondering WHY the arena sets are stronger.... If you have the full set, the enemies defense is reduced by 1000/1500/2000. That translates into 500/750/1000 more damage for you. (attack - defense)/2 is damage dealt. You also get a tasty rage bonus at the start. The ONLY exception to this is LONG battles like Forgotten Catacombs fights. In those fights, the x0 sets 10 extra rage per attack is ENORMOUS.


Also note that you need certain Honor rankings to be able to purchase the sets, Honor is gained in Battlegrounds by killing other players and in Guild Battle.

And last note, if you only have 2-3 pieces, don't bother. You need to have the FULL set on (all 4 items) to get the full use out of the x5 level sets.
Oh, and don't forget to fully enchant it :p


Jewels/Rings/DIAMONDS!
Err.. Right, well, the other 4 equipment slots.
The best and really only viable accessories once you get past L40 is the accessories from the Forgotten Crypt shop. They give set bonuses like the arena/X0 level sets and they are also the most powerful pieces of gear you can get. They can also be turned into Legendary items via synthesize. This requires a GIANT amount of stones that can only be gotten from running Nightmare version of the MP campaigns. Once you get enough stones (and the other items from the crypt shop) you can turn your L40/50/etc accessories into legendary versions.

The legendary versions have two advantages. First, they can be enchanted to a higher level, giving you MUCH higher bonuses. (at the cost of freakish amounts of gold) Second, if you are a cash player they gain a fourth socketing slot. Which is great if you have a ton of socketing rods to spare....

And in case anyone is wondering, once upgraded legendary items keep any sockets you have opened on them as well as their current enchant level.


Gems
Gems are key to maximizing your potential.
The primary place to get gems is the Forgotten crypts. You can also get them from Altar spin as well as Battleground chests. If you have balens you can buy them from the Market shop. (Market is a REALLY good place for gems if you don't mind spending money)

First thing to know is that L1-4 gems slowly gain power. L5+ gems are DRAMATIC increases over their prior versions so you want to shoot for getting L5+ gems.

Several things to know about this though. If you are a free player, all equipment except your weapon has ONE slot to put a gem in so picking the right gems is key. You can use socketing rods to add slots to pieces of gear (up to 4 gem sockets per piece) but you only get 4 socketing rods from quests and the rest come from BG Chests/Altar spins/Spire chests but they are VERY RARE so use them sparingly. I used several on my L45 gear (which was stupid) and I'll use several more on my L55 gear but...... Take care when using socketing rods. I would personally recommend that if you are a free player that you save ALL your rods for your L55 gear.

As for gems themselves. It's VASTLY cheaper to convert (via blacksmith) high level gems than it is lower ones. For instance, to convert 4x L4 gems costs 160k, to convert 1x L5 gem is 80k (takes 4 L4's to synth a L5). So ALWAYS convert your highest level gems.


As for who uses what gem type. My personal preference is to shore up holes in each class once you get done with damage.
Mages:
MATK
PDEF
HP or MDEF (MDEF mostly for Crypts since the boss there does magic damage; personally I'm stacked for MDEF and I hunt other mages in BG etc, but that's a personal choice)

Archers:
PATK
Crit
HP
MDEF
PDEF (archers have crappy def all around)

Knights:
PATK
MDEF
HP
After that it's your choice based on skills, PDEF, Block, etc


Refinement
Refinement is another key piece of equipment. Normally you get whatever random crap bonuses your gear spawns with...... Well, I'm sure you've all seen the crap that can spawn.
If you recycle those blue/purple pieces of gear you get from MP dungeons and campaigns you get refinement stones that can then be used to refine the gear you actually use.

Unless you use balens to lock in certain stats, refinement is basically a.... well, cross your fingers and hope setup but there's some things you should try to get on each piece of gear.

Int/Strength. (depending on your class, Archers/Knights need Strength, Mages; Int) This should be on most/all of your gear. It gives 4 per point to your attack and 1 per point to your def. So if you have 20 int on a piece of gear that translates into 80 MATK and 20 MDEF.
Defense. This is HUGE. Get it. 4 MDEF/4PDEF per point.
P/MATK - Dur?
Endurance. 20 HP per point.

Beyond those three, it's up to you, most classes should go for the same sorts of stats they would use for gems. Often, you will have to settle for two of those, if the other stats are decent, go for it.

Also know that stats range from L1 to L10, the difference between L1 and L10 is fairly tiny prior to L50 but after that it starts to increase at a fairly substantial rate.

For those willing to spend the balens, LOCK IN YOUR IDEAL STATS WHEN YOU GET THEM!
Seriously, you can make crazy good gear.


WORKING ON THIS, I need more information about Knight/Archer astrals since I'm a mage, I just listed the obvious ones for them.
Astrals
Astrals are the other place beyond gems to fill in holes in your build.

Astrals go in terms of power:
Green -> Blue -> Purple -> Orange -> Red

With Red being the best.

A couple of things about this, only the 5th astral area can give Red astrals; 4th/5th can give orange and it's random if you get access to the next level. 3rd/4th/5th area can give purple.
What's an Astral area? Bottom of the astral screen, there's 5 possible places for you to click. The higher level ones only open up if you get lucky on the lower ones.
Magus Star -> Ceres -> Pallas -> Satum -> Chiron

So basically you are spending gold in the hopes of the higher level astral area's opening so you can get a chance at a red/orange astral.


Personally, I sell all grey/green astrals and use the blues/purples to feed the ones I actually use. Some people feed green/blue/purple but the greens give you almost what you paid for them, thus giving you more points in the long run if you sell them. And you will need points to trade in for Red/Orange astrals since your odds of getting the ones you need are slim.

What are points? If you click on "exchange" next to the points listed you can turn in your failed/crappy captures for Red/Orange/Purple astrals. Meaning that if you got 10000000 grey astrals in a row, you can turn that in for all the Red astrals you ever wanted. Keep this in mind, Reds cost 15k astral points, Oranges, 7k points.


Expect to spend MILLIONS a day to get the astrals you want and to feed them Higher level astrals have HUGE XP costs. If you aren't spending millions a day, don't bother. Get the guild skills since they are a much bigger boost. (for instance, my astrals are all L3-4, any higher will cost insane amounts so I'm just getting guild skills maxed for now)


Now, as to WHAT astrals to use:
Mage:
MATK - This is what you want as Red/Orange. Get it.
PDEF - Mages have horrible PDEF.
MDEF - Insanely useful in Catacombs and against other mages.
HP - Kind of self-explanatory
Enhanced Will Destroyer - This is really ONLY useful if you have an orange version of it. 5% damage increase per level, disables crit. Yes, it's worth it unless you have all your gem slots filled with crit gems in which case... Get help.
Goddess Blessing - % reduction in all damage. Handy, get it once you hit 60.

Archer
PATK - Why are you even asking?
Crit - Archers are all crit based, the more the merrier.
Determination - Increased Crit damage. GET IT!
PDEF - Archers have horrible defense. Get it
MDEF - See above
HP - See above

Knight
PATK - Derp.
MDEF - Knights have very bad MDEF, get this.
Block - Skills and talents to help with block, this is VERY good later on
HP - Why wouldn't you?