That how you imagine thief. I imagine a thief more like garrett from Thief: The dark project.

when i think rogue i think a stabby-stabby thief who can (sometiems likes) to fight, but when i think thief i think someone who uses his wits to avoid a combat situation

At first I would focus on sneak, light armor and archery. Keep a dagger close by for when [censored] gets real.

A fourth perk tree of your choosing based on what you use to supplement the other 3 by lvl 10 or 15. By 35 you will have all the perks you want in those categories. Then you can go further if you wish and will be a BAMF in skyrim.

Any thief build must have:

Sneak – Obviously.

One handed – if you need to do combat, synergizes pretty well with one handed and daggers for good crits, remember to bring daggers for a sneak attack, and a sword/axe for open fights.

Pickpocktet – You’re going to be a thief don’t ya? You should use this. Is a great way to get rich and also quite fun once mastered

Light armor – as good as you can be as a thief, you need some protection. Also thieves’ guild armor is this one. I still have to try an armorless rouge….but not now

Additionally you can choose to have:

- Illusion – A thief best friend. Get muffle early so you can level up the skill and be as silent as you can. Once you get it to 75 learn how to become invisible and you’re golden.

Or

Alchemy – for a more mundane approach. Use poisons to dispose of enemies and aid you in combat. Learn to make invisibity potions and keep a dozen on you at all times, if things get ugly (they will) use one and run to the shadows.

Archery – A pretty Powerful combat skill for any sneaker. You can use it if you want, but at least I prefer the more close and personal feel on a thief. A must have if you intend to kill dragons.

Also, eventually you will want to take Smithing and Enchanting, my advice, leave them for last after you have mastered all your core skills or if enemies are giving you a tough time….believe me: once mastered, those two skills will allow you to become a demi god.

Also join the thieves guild ASAP, you will need a fence to sell all of your stolen loot. Also, if your bounty is low and the guards are after you, find a safe place to stash your loot, and turn yourself in. After getting out of jail, recover your things and keep thievening. Maybe isn’t necessary, but adds some flavor to being a thief.

Here is the arcane-thief build I've been using, with great success: http://skyrimcalculator.com/#78380 Hopefully that link works

At the beginning I worked on getting certain perks in archery and light armor, only then branching out to the perks I wanted from various schools of magic. Was only around when I hit level 50 that I concentrated on getting perks in enchanting, smithing, and alchemy. With less on smithng since with a high conjuration and the completion of a certain quest I was able to make daedric weapons, which are arguably the best in the game.

my thief is named sleezy judas and all he does is sneak, steal and exploit people for more money. I got somthing like over 50 thousand gold, because you should increase your barter to 5 and get the merchant perk. don't bother with the investment.
Pretty much all the green star constellations in the skill tree are useful for you, use daggers and a bow and you will be fine.

Investment is great.

River wood trader gains 10k gold.