BS / Enginering, is the balanced way. Engi ench @ Gloves hyperspeed accelerators (340 haste on use) unless you're playing x2 dps comp.
Then you'll go for Hand-mounted pyro rocket (1654-2020 dmg on use)
Tailoring / Enginering, For x2 dps comps, heavy burst. fits well with proc based trinkets, read down below.
BS / JC, Sustained dmg. If you're low on resil you could even use the 34 reil gems to boost it abit.
Enchants / gems.
Head: Ap Resil ench.
Shoulders: Ap Resil ench.
Cloak: Flexweave ench.
Chest: 20 resil.
Bracers: 50 AP.
MH: Berzerking and Woundpoison.
OH: Titanium weapon chain and Deadlypoison.
Gloves: Engi ench Haste / Pyro, i prefer Haste for better poison uptime.
Legs: 75 AP 22 Crit.
Boots, Rocketboost if you're doing other things than arenas, else i'd go for the AP ench or hit/crit if your hitrating is too low.
Gemming: Relentless Earthsiege diamond in head.
Nightmare tear in the blue socket where the bonus benefits you the most.
Try to be somewhere near 1K resil, since you do not have the same kind of mobility that a sub rogue has.
Which pretty much means that you fit the yellow sockets with resil until you're around 1K rest 40 AP gems.
Gearing.
There are several ways of gearing an evenom rogue.
Ill only bring up the most officient gearing paths.
Trinkets.
First, Proc rogue. (Human) If you are going for this you'll need STS and WFS trinkets.
This way you'll max your dmg output at opener. This is typical for x2 DPS comps.
(Other races) Sts / Medalion
Sustained rogue. (Human) For this you'll either go DW HC / DW normal. Or DW / WFS, since WFS provides alot of base Crit and it will put your sustained dmg in a good state.
Both of these paths have really good Base stats and will cause heavy dmg even when procs are down.
(Other races) DW / Medalion
Balanced rogue. (Human only) Pretty much Sts / DW. This way you'll have decent burst and decent sustained dmg.
Mainset.
Full WF set or Lady 25 hc shoulders for the extra haste.
Offensive Offset.
(For Human) WF Boots / Belt, RS 25 bracers, Shadowvault cloak, Woodin's Neck or Precious collar (Optional.) Gluths Thrown.
Weapons. Heavenesfall MH. WF Oh (1.8.) Signet of Twilight / Icc rep Finger. A very solid build for most situations.
This will put you at 1K resil which you'll need since you're less mobile than Sub rogues and will find it tricky to escape situations where sub rogues would make it out with a breeze.
(Other races) Pretty much just like above except that you'll have free resilience from Medalion, so you can drop WF belt for Astrylian. Or another heavensfall instead of Wrathful OH for maximum amount of haste.
Defensive Offset.
Full WF including both daggers (both 1.8.) I'd only suggest this in certain scenarios, while playing with a disc priest for example, it provides alot of utility.
(I only put on full WF offset if i know ill face x2 DPS comps that will train me the entire game.)
Stats Explaination and priorities.
Haste: Provies good uptime on your poisons and scales really well with 1.8 offhand for maximal dmg output.
Hit: You can never get too much hit as an envenom rogue. Hitcap for special attacks (Mutilate, Envenom.. etc.) is 5% in general and 6% for elfs.
But for whitehits the cap is way higher, simple math - the more whitehits you get, the better uptime of your poisons, which is the core of your dmg output.
Crit/Agi: both really good stats, more crits higher dmg right? This is why i don't use WF Cloak / Neck / Finger in general, cause they don't have any agility and it will drop your crit stat really low.
Resilience: for survival as we all know, the amount is alot about preferance and it's very situational.
Not to go too far into detail i'd say a good amount of resilience would be 1K as assasination.
Arp: Not a stat you wanna aim for since your primairy dmg comes from poison and Envenom ignores armor.
AP: Core stat. After you've reached suggested resilience you'll be maxing out AP as much as you can.
Deadly poison offhand, wound mainhand. Incase you're having a hard time keeping deadly up vs restodruids / hpaladins spam cleansing deadly you can use shiv and envenom right after just to get the extra procrate, after that you sould have no issues keeping the dmg where it should be at.
I hope i cleared out alot of questionmarks with my basic setup guide for Assasination rogues. If you have questions about how it's playd in certain matchups just PM me ingame and ill advice you, Peace! / Rikuri.