Hello everyone. I've played as as Assassin, so here are my tips.
Stats:
CON: You can put some points into CON, alike 25 but nothing more till DEX and STR are maxed because; more AC means more pierce and you can get HP trough items.
INT: Keep it on minimum, useless.
STR: After DEX is maxed, and CON is alike 25, max this.
DEX: Max it.
Skills:
PVM: You should upgrade skills in this way; Ghost Attack, Getaway, Rapid Charge, Poison Nova, Stealth.
PVP: You should upgrade skills in this way: Ghost Attack, Poison Nova, Rapid Charge, Getaway, Stealth.
note: maybe some people will not agree with me but, since exp rate is high, no matter in which way you will ugprade the skills.
Some PVP tips:
Start a duel in range that you can use Posion Nova skill. Open with Poison Nova because, there is a high chance that target will get poisoned. Afterwards, when target gets to you, use Ghost Attack. Third, there is a little trick. You will use Getaway but like this: hit the target 6x (if the continuum is not turned on), and, when you've hit the target 6th time, use Getaway to make a combo. Best combo is 4x. If you dont do like that, you will hit the target only with 1x Getaway, but with this combo, you can hit like 4x Getaway. Practice it on monsters before you start on people ;). 4th skill should be Rapid Charge. Use it immidiately after Getaway is finished so you can get faster to your target ;). After you've done, you can start piercing the targer with your daggers ;). Some people maybe think that Stealth is good opener because it raises your Ghost Attack damage. Well, thats true but, imo, poison makes much more dmg than one Ghost Attack so.. ;)
Maybe some of you wont like this, im just saying what i've done and it worked well for me.