pimp me an assassin

[Shadowscale]

So my older brother said I could retrain my character in his campaign, so I decided to make a gnome rogue which will eventually prestige into assassin. Could someone help me build this into an effective monster of a character.
whisper gnome
Strength 10
Dexterity: 20
Constitution: 16
Intelligence: 18
Wisdom: 12
Charisma: 14

All pathfinder books are allowed except ultimate equipment and I was allowed to use only the whisper gnome from d&d

I was going to use only daggers along with the knifemaster archetype
Obviously weapon finesse should be taken at first level.
Beyond that though I don't know what to do with this character so I could use some help. Want to go into assassin as soon as possible. Please help me opimize

[Snowbluff]

I have this one named Candy...

Okay, how about picking up Hellcat's Stealth? Hide when you don't have any shadows?

What are you focusing on? Death Attack? Damage? Assassination?

[Sayt]

I'd actually consider the Stalker over the Rogue. Comparing Rogue10 vs Stalker10, you're up 3 BAB, down 2 sneak attack dice, but also get a +5 favored target to attack, damage and several useful assassin skills vs a target, which helps with the flat damage.

Stalker can, like rogue, get the fastest available access to Assassin, and has poison talents which are synergistic with assassin's poison resistances. I'd also suggest Piranha strike if you do go knifes, as it's basically Dex/Light weapon power attack.

That said, the vanilla assassin class isn't that great. On the Other hand, Crimson/Red Mantis Assassin (http://www.d20pfsrd.com/classes/prestige-classes/other-paizo/c-d/red-mantis-assassin) advances Sneak attack, has an assassination-like ability, offers 1-4th level spells from the Illusion and Transmutation schools of sorcerer/wizard spells, and Verminshape II as a SLA, and again, Slayer 5 gets you in perfectly.

For entry, I'd probably go
S1: EWP: Sawtooth Scimitar
S2: Talent: Finess Rogue
S3: TWF
S4: Talent: Weapon Training (Sawtooth Scimitar)
S5: Alertness

On the other hand, if you're playing from level 1, I'd maybe take Weapon Finess at 1 and use the Combat Trick Talent to pick up EWP Sawtooth Scimitar.

Edit: I also suggest picking up Hellcat Stealth, as Snowbluff suggests, and I'd consider dampen presence, which lets you hide from a few of the more common detection methods.

[Zanos]

Do you have to have Assassin written in your class field on your character sheet?

Vivisectionist Alchemist makes rogues cry in damage output, and the Saboteur Archetype for Gnomes(which you already are, yay) can help with stealth.

The only abilities the Assassin PrC gets are extremely situational and base rogue is notoriously bad in pathfinder.