I rather expect this to turn into a long thread. So please feel free to add your own suggestions that you think everyone should know. Please be considerate, new people will have to read through this. I'm sure they will appreciate if you leave out the truly obvious. This is for beginners, but is not intended as a tutorial.
Regarding Disposal of Excess Inventory:
It's pretty obvious that you can sell things just about anywhere. But there are ways to increase your cash flow.
First off, there are the Marketplace Pawn Shops. While they do specialize in weapons, armor, clothing or Jewelry, they will pay a great deal more than a Bar Keep or a General Vendor. It also bears mentioning that the higher your Haggle skill and your Charisma are, the more you will receive in return for your items.
But that's not the extent of the pawn shop markets. In House Kundarak, there is a little out-of-the-way shop (near the Teleporter) for pawning higher level armor and shields than the Marketplace dealer will accept.
Likewise, in House Deneith, there is another shop where you can Pawn higher level weapons.
Both of the last two have three different level vendors. They are not divided evenly by level, unfortunately.
If you belong to a guild with the "Three-Fingered Thad" hold room amenity, and you have really high level items to sell, you can go there. As yet though, Thad's vendors do not purchase anything like low-level items.
And finally, if you're interested in pursuing crafting, you may take your items to one of the Crafting Halls. There is a crafting tutorial available in House Kundarak. There's another Crafting Hall in the Cannith Enclave. And many of the larger guilds have a Cannith Crafting Hall in one of their Staterooms (large amenity rooms).
I'm mostly of the opinion that Crafting is best trained, in voice conversation, live in the game.
Especially since the new crafting system went into effect, the nuance level is far too complex to cover in a single post. Unless it's an extremely long one, of course. I've been working at it for a while and there are still many things I don't know. I'm thinking there's a large number of things that just need to be learned by doing.