Question for you, strigori. I was thinking about creating a new character and going with a thief, focusing on sneak and archery. As an assassin, and somebody who doesn't have a lot of armor, are you able to easily avoid large confrontations and how do you fare against dragons?
Furthermore, when you can't avoid large confrontations, how do you survive given your relatively weak defenses?
Your sneak skill will go up pretty quick, and I would recommend investing in most of the perks in the tree, I only took one point in the Stealth perk though, I never felt I needed any more ranks there. And Shadow warrior was a situational skill, The Backstab arm should be your #1 priority, the damage bonuses from those perks make the whole build viable.
When you get close to a dungeon or fortress, you pretty much stay in sneak from there on out, and generally speaking, I ended up waiting til night to start my assault on most places with more than two enemies. By being careful and using Aura Whisper a lot I was able to control my confrontations most of the time. Often my approach to a room would be Aura Whisper to see where the targets were, snipe one with with my bow, and back up around a corner and wait for hidden to show back up, usually only takes a few seconds. If backs were turned to me, or I could get around behind someone, Backstab was my best friend, especially after getting the Assassin's Blade perk, with a good dagger most things go down with one hit. It gets even more powerful if you follow the Dark Brotherhood quest line too.
When I couldn't get into a sneak position, and many quests have spots like this, it became a damage sprint for me. I didn't worry about blocking and just dual wielded swords for those encounters, and made good use of the power attacks and poisons. Poisons and potions definitely help, even without spending perks in the tree. Some fights I ended up popping healing potions like candy. I liked having a paralyze poison or weapon with that enchanted on it for a helping hand in some really tough fights.
Dragons were not that big an issue, just using the bow, and a resist necklace of the right kind for them. Just don't let them get close to you, or you get to see the cool animations where they eat, or throw you.