There's a lot of information so I will try to be as concise and specific as possible. I'm writing this guide under the assumption that you already possess some general knowledge about this class.
The most common thing I am asked is gear and tatoo setups for the class. Let's begin.
What weapon should a sws use?
This is actually one of the best things about playing this class. A sws can sing with any weapon. In PvE, typically a sword is the best weapon. Some people swear by a focus SA dagger and a bow is good for archer xp groups. I've seen sws use all sorts of swords. Some prefer double handed swords and some even use dual swords. Despite popular misconception, dual swords will out damage a single sword despite the masteries a sws recieves.
In PvP, without a doubt a bow is the best weapon for a sws with a melee weapon as backup. I prefer the single sword and shield combo over duals and double handed swords. A shield will block 100% of archer attacks as long as you are facing your attacker and it reduces arrow damage by 25%.
The range, critical rate and patk of a bow offer so much more than any melee weapon. Although the dps is higher with a melee weapon, typically most sws never reach their target before it dies or spend most of their time chasing their target instead of hitting it. A bow solves these issues and a UD'ed sws with a bow can be quite a nuisance.
What is the best tatoo setup?
A damage dealer build is the best build for a sws, meaning +5 str -5 con with +4 wit -4 int. This should be coupled with a DD armor set like Blue Wolf, Tallum, or Majestic Heavy. This allows a sws to achieve over 40 str where they begin to recieve larger bonuses to patk (discussed in detail below as well as +dex).
A +con build sws are probably the worst build for a sws. The larger bonuses for hp are after 43. The only way a sws can achieve this is with Doom Heavy and a +5 con tatoo.
In PvE, a sws is never tanking unless you solo. What's more important in soloing is your pdef and that your healer isn't sleeping at the keyboard. The same is true for PvP. A sws shouldn't be targetted first because the healers and DD's are higher priority targets. Even if a sws is targetted you can always use the skill ultimate defense.
Here are the stat changes of -dex.
http://img81.imageshack.us/img81/3571/minusdex7vd.jpg
These are base stats and level does not affect the bonuses from dex. Each -2 dex is -2 accuracy and evasion. -5 dex is about -4% in your attack speed. Each point of dex lowers run speed and critical by 1.
This is the stat changes from +dex.
http://img30.imageshack.us/img30/9684/plusdex8io.jpg
This is the reverse of -dex. Each point of dex increases your critcal rate and run speed by 1 (ss was taken with ww2). +5 dex adds +4% attack speed. +1 dex adds 1 evasion/accuracy and +4 adds 2 because of the way accuracy and evasion are calculated.
This is the stat change of +str and +con.
http://img90.imageshack.us/img90/9819/plusstr1hv.jpg
Going from 36 to 40 strength is an increase of about 4% in patk. Each point of con is 115 hp (at level 76) and about 50 cp. This is linear in either direction you are going. To keep it simple, it's about 100 hp and 50 cp for each point of con after level 40.
This is the stat change of +str after breaking human default stats.
http://img90.imageshack.us/img90/6563/plusstr24xb.jpg
Going from 40 to 43 strength is an increase of about 10% in patk. Strength is the stat to increase if you are looking to increase your damage. The bonuses, and lack of, from dex are barely noticeable, with the exception of attack speed and accuracy. There are no heavy armor sets that give bonuses to dex and there are no bonuses to dex for increasing it beyond a certain point, unlike strength. If you are planning to go +con (which I do not recommend) it is much better to lower your dex than your str to keep your damage up.
Finally, here is +wit -int.
http://img87.imageshack.us/img87/1631/pluswit4gm.jpg
This lowers your matk by about 15% and increases your casting speed by about 21%. Personally, I have found that entangle has a low landing rate (even with bsps and without -int). The +wit will help against debuffs like root and sleep.
If anyone has questions I will answer them by adding them to the guide.