So, my last character, a magic based assasin was fun, but i didn't invest perks properly so I gave up

How would i do this early on? Id need a decent sneak, and then 50 illusion for the silent casing perk.
Any help?

Muffle to augment your sneaking early on - this levels your illusion skill very quickly indeed, especially if you activate the Mage stone...

Thank you

Frenzy combined with quiet casting is a good way to get rid of guards without making yourself obvious. Paralyze and invisibility will also come in incredibly handy.

Ya just invest points into spell augmentation rather than cost reduction.

mage assassin sounds like a fascinating combination. Good luck with your build.

Here's my perk build for my nightblade assassin. I did not perk the left side of the sneak tree because I rely on illusion magic (muffle/invisibility spells) rather than the sneak perks. I have a different character who took those sneak perks but does not rely on illusion magic. I went for enchant rather than cost reduction perks, but you could switch out enchant for the illusion cost reduction perks if you want.

Archery 8
Overdraw (5)
Eagle Eye
Steady Hand (1)
Power Shot

One Handed 5
Armsman (5)

Alchemy 8
Alchemist (5)
Physician
Benefactor
Poisoner

Illusion 9
Novice
Hypnotic Gaze, Aspect of Terror, Rage, Master of the Mind
Animage, Kindred Mage, Quiet Casting
Dual Casting

Enchanting 8
Enchanter (5)
Insightful Enchanter
Corpus Enchanter
Extra Effect

Sneak 4
Stealth (1)
Backstab
Deadly Aim
Assassin’s Blade

Thanks everyone
I'm going for a varied character.
Sneak
Illusion
Destruction
One handed

One handed is mostly for RP, he was taught to use blades as a child
He aspires to be a Mage (illusion, destruction.)
He then spent all his money on mead in Riften, after the trauma at Helgen, then got involved with the theives guild.

Later to join the DB...