This is an easy and probably the most common build you can find.
Most unfunded Assassins decide to go this way since they do not have
to scroll their items for more DEX to use their weapon. Assassins
have very low weapon attack based on the claw. You see level 70 claws
with around 50 attack and yet you see other weapon with 100+ attack
at this level. This is why we need to use every weapon we can.
Fortunately with this stat build you will be able to do this.
Basically while you start out make sure you have 4 into STR and 4
into INT. Then continue on with this build.

Level 10- 25 DEX
Level 15- 30 DEX
Level 20- 40 DEX
Level 25- 50 DEX
Level 30- 60 DEX
Level 35- 70 DEX
Level 40- 80 DEX
Level 50- 90 DEX
Level 60- 100 DEX

Just add 1 DEX per level after level 60 and you will be able to
use every equipment afterwards.