I was wondering when the leveling curve starts to become a problem. I'm lvl 15 and my highest skill is 43 I think and yeah....I've noticed I have to cut on guys barely wearing any armor A LOT to kill them. Meanwhile my companion can drop most anything with their 2-handed weapon in 3 hits or less.
And there's like...at least 9 quests involving the Thieves Guild. I'm impressed. I don't necessary like playing the equivalent of a mafia thug in my medieval RPGs....but it's pretty neat how, once you get past that, there's this whole organizational setup. Way more elaborate than Oblivion's Thieves Guild, which was kind of a disappointment. And everyone's got a personality, the kind of treatment the Dark Brotherhood quests got in Oblivion. Me likey.
Could someone share his way of gaining fast cash?
Depends on how much you need. Generally, people leave coin pouches EVERYWHERE in the game world. Every house you visit has probably between 10 and 20 gold just laying around out in the open. Another 20 probably scattered around in containers. Iron or better breastplates and shields sell for between 20 or 30 I think without any real skill in Speech, so I always collect them when I find them. You seem to have an insane weight capacity in game since there's no stats, and a companion can be loaded up with tons of heavy crap. It all sells and its everywhere. When you pick up anything worth more than 60 gold pre-vendor, it adds up. Not as much as it has in previous ES games, but I made the ~6250 you need to buy a house in Whiterun and outfit it pretty easily.
You can also try mining ore, but you might have to refine it first to get as much out of it as possible, which requires finding a smelter.