A few sugestions for you:
At point buy system don't go for the 18 if you are not a caster. To bring your stats from 16 to 18 will cost you 6 points (not worth the effort, for that number I can get a +3 bonus at other stats).
Strength is not a major isue for a rogue, try to keep it neutral (10 to 11). The bit extra to hit is nothing compared dexterity, and weapon finesse solves a lot. The dammage is not worth the trouble, sneak attack makes up for that enough.
Dexterity is nice, but don't over do this stat, as a rogue you want to be versitile. If you got the points a 16 (in your case an 18 with the +2) will do more then enough the trick, but most likely I would take an 15 and use the stat raise from level 4 to get an 16.
Constitution is importand, its a major saving throw of instand death spells and poisons. Also the few extra HP never hurts. Get this atleast at 12, but if you got points left 14.
Inteligence, no questions here, search and more importand skills work on this, 14 atleast
Wisdom is also great for spell saves and your spot/listen and sense motive rolls. Still if you need a low stat this one could be a 10 but watch the hold persons then....
Charisma is the stat if you want a social rogue (bluff, diplomacy, use magic device, etc). I would never put it below 10.
This would make atleast:
str 10, dex 17, con 12, int 14, wis 10, cha 10 (what is 26 points, and you can raise con, wis or cha with 4 points).
Importand feats for a rogue are:
Weapon finesse
Improved Initiative (for that extra sneak attack)
Iron Will (hold persons, and other will saves..)
I also would consider to get a level of wizard. And if you are higher level, 2 more levels for a total of 3 (I love see invisibility, alter self and invisibility for an rogue). Specialize in what ever you like and throw out Invocation (you don't need or want dammage spells). This will give you detect magic (handy for magical traps) detect poison (handy for normal traps) feather fall, exp. retreat, comprehend languages and much more fun stuff, and that one level is not gone hurt you much in the long run compared to the bonusses you get and the free +2 on your will saving throw.
Thats about it,
have fun,
Lai