Tricky gave some great advice, Drath has the outline of how a DPS rogue should have points spread out, but a player build more importantly should be centered around how you actually play the game, including how you train. Are you trying to solo a lot or do you like to team up with others to kill? There are some good build guides in the rogue section of the forums, but keep in mind, most of them are centered around their gear and how it can impact the total numbers. Stat placement is important, however, there are still other things that factor into how total damage is calculated by the game, including and especially player level.
Best thing to do is to buy a book of Rebirth, apply the points in small sections at a time and watch the numbers like total damage increase as you save the changes. Before you apply the points try to put on your gear including weapons you use regularly, then apply the points as needed. Start off with say 5 point increments at a time, then save and note the changes. I believe after 300 the total value from increasing strength begins to deminish, so depending on level and gear, I wouldn't go overboard with it. The value of even a low level 10-15 DPS ring will outweigh putting another 30 points into strength after a certain point. Remember this, if you are laying there dead or running back because you have no points in health and die from a single boss strike, someone else is still alive and probably going to get the kill.
Equipment definitely plays a large role in DPS, including damage rings, bracelets, armor(radiant/earthstone vs frozen/diamond) and you may difficulty finding some of the really good gear, partially because it is rare. Work with what you have now and try upgrade over time as you play the game.
As for skills, maxed poison weapon can add more to your damage numbers and continues to do so because it lasts for a little while versus using Sneak or Assassinate which are one and done until they can be recast. Sneak and Assassinate also interrupt your attack to be cast and while they seem effective should only be used at the beginning or end of a battle. While you used your one 1200 damage Sneak attack, I just hit the boss 8 times with and average damage of 200 per hit...guess what, I win the numbers game. I myself put the most value in Poison Weapon, Smoke Bomb, Fast Reflexes and Quick Strike(if used correctly). Aside from Sneak and Assassinate, the rest are fairly worthless skills that sound good, but do not impact stats enough to use those over the others I mentioned.
Last thing is, yes rogues should get the kill most of the time as the DPS class, but honestly who cares as long as you are having fun...I know I don't mind if someone else gets the kill as long as we killed the boss and had fun while doing it. If you want to solo kill and not die a lot, build a Ranger and watch some of the higher levels use Bolas to solo bosses...very impressive.
