I've got 184 hours into the game, so I'm fairly familiar with a number of its aspects. I am currently playing a character that seems awfully powerful - I haven't died in a long time.
Briefly, she is a level 34 Breton stealth mage specializing in Conjuration, Illusion, Alteration and Sneak with over 40,000 Septims, 360 Magika, 210 Health, 130 Stamina and 9 perks left to spend.
Conjuration because two Demora Lords kinda own most everything. Conjuration 100, 10 perks.
Illusion at 71 and 7 perks for Muffle, Quiet Casting and Rage. Casting Frenzy on any one of a group of foes causes bedlam - fratricide on a grand scale.
Alteration at 70, 5 perks, for 30% Magic Resistance. Add 25% for Breton and 25% for Lord Stone gets you to 80% Resist Magic. The cap is 85%.
Sneak 86, 1 perk. I've also got 45% increased Sneak from Thieve's Guild and Dark Brotherhood gear. If they don't know you're there everything's copacetic.
The basic tactic is to sneak whenever you are in the vicinity of trouble and have two Dremora Lords summoned. If you're not geared for Muffle then have the spell up. You don't have much opportuntity to cast Frenzy in dungeons, but it works wonders on forts and the like. Spot a guy on the wall and hit him. If your Dramora Lords get killed just summon two more. Hey, they don't know you're there.
So, how did I get here? Well publicized exploits! Cheating? So sue me - meanwhile I'm kicking patootie. Start in Riverwood and chop firewood until you get 3,000 Septims. Go to Dragonsreach and buy Soul Trap and Muffle. Cast Soul Trap on a dead body, the wolf on the road, until you reach 100 Conjuration. This is quite tedious. Tip - when out of Magicka rest one hour (very quick), rinse, repeat. Now go back to Dragonsreach into the wizard's room behind the map, face into the wall, go into sneak and press "C" (PC) to run continously whilst casting Muffle as often as you can. Do this until Illusion gets to 70. Put all level-ups into Magicka. So how about Alteration? Southwest of Whiterun there is a lone giant in a camp. Go up into the cliff above him, go into sneak, hit him with someting (firebolt, lightning, arrow) then cast Oakflesh until you run out of Magicka. Rest one hour, rinse, repeat - you know the drill. When you get to 50 go to Riften and buy Detect Living at the Jarl's place. Quick way to get it to 70.
Start your questing with the Thieve's Guild. Continue until you get the Skeleton Key - don't go beyond to complete the sequence. Next, do the Dark Brotherhood line. The reward for killing the emperor is 20,000 Septims. After these two lines you have lots of moolah, infinite lockpick and super sneak along with max magic resist. What next? Don't know. Should be interesting.