I'm going with a proper assassin build based on the rogue subclass from D&D.
That means I'm not touching magic, though magic items and scrolls are okay.
I'm maxing Sneak.
Lockpicking gets only the main perks that make it easier, Locksmith, and Unbreakable because lock picks don't actually break and taking any of the other perks steps into Thief territory rather than Assassin.
Pickpocket only gets Light Fingers, Night Thief, and Poisoned to discreetly poison enemies.
Speech is optional, but maybe just go up to Intimidation.
Alchemy gets a bit for poison crafting, but not much else.
Light Armor can be maxed whenever - it's not a priority because ideally you don't get spotted.
I'm not really going into Archery that much. x30 Sneak Attack from Assassin's Blade with Shrouded Gloves versus x3 from Deadly Aim... Don't really need it. So for roleplay reasons, my assassin isn't too great with a bow. When ranged attacks are necessary, he'll use a crossbow.
One-Handed gets a bit because more dagger damage for assassinating is great.
Take Smithing just a bit for Arcane Blacksmith to upgrade the Blade of Woe and Shrouded Armor.
It's shaping up to be a decent D&D inspired build. I'll make more eventually.