The first game has a tutorial section in which you learn how to control party members. Many players found they could loot the inventory of party members of valuable items (such as a + 1 shield, a wand of heavens, and healing potions, and nonmagical plate mail), and then export their characters, and simply start a new game with said character—who now starts off with enough armor and money to breeze through until the first major dungeon.
Also, in the section just outside Candlekeep, to the north, you usually will "randomly" meet Drizzt and a party of his friends. By saving the game here and having Imoen attempt to pickpocket him successfully before he exits the screen you could end up with both of Drizzt's +5 named artifact scimitars!
Using a couple of cheap potions, a few valuable items and some Save Scumming, a player could sell an item to a fence, steal it back and then sell it again. With a couple of potions of master theivery, you would almost never be caught.
There is a chunk of Ankheg-infested farmland in the map just north of the first real haven of the game. Ankhegs are worth quite a chunk of XP, but being correspondingly deadly, a patient and/or lucky player could gain a few levels in short order. You can also sell the ankheg shells for gobs of cash and have good armor crafted from them, though you would need gobs of cash for the latter. All you have to do is avoid the ankheg attacks, which are slow but virtually One Hit Kills at low level—and they have a vicious ranged attack.
A better way to get a ton of XP early was to buy a Scroll of Protection From Petrification and then go kill the basilisks near one of the early towns. They gave about 7000 XP each and were fairly trivial as long as you couldn't be turned to stone. If you wanted to solo the game, you could gain a number of levels very quickly this way.
Algernon's Cape grants the use of an at-will, instant-cast, virtually-unlimited-ammo Charm spell to a first or second level PC five minutes into the game through a ridiculously easy pickpocket or NPC kill (approximately 4 HP) - yeah, that's a game nuker. An easter egg, to be sure, and serious players who wanted to enjoy the game wouldn't use it, but still. There's nothing quite like turning an enemy party against itself. You could win the whole game with one character, never having to raise a fist. Of course, no kill XP, but then that's what quest completion XP is for.
There are a few really well hidden secret containers in early maps. The first map after out from Candlekeep has a diamond, worth a good 500 gold; the Lion's Road map has a + 1 ring of protection; the Friendly Arm inn has a ring which doubles the wearer's first-level spell slots if they're a wizard; and though not precisely early, Nashkel still takes place in the first act and has half-weight + 2 plate mail.
Shadows of Amn
After importing a character from the first game, if you quickly pause just before hearing the character gasp, you can drop their entire inventory, and thus prevent it from being swiped by a script. This allows you to keep some powerful end-game items from the first game (including the Plate Mail/Two-Handed Sword +3 from Tales of the Sword Coast), which are easily good enough to see you through most of the game.
It's possible to venture into the Throne of Bhaal bonus dungeon, Watcher's Keep, during Chapter 2 of Amn and pick up ridiculously powerful gear. Granted, the enemies are far beyond the current party level at that point, but using Yoshimo to sneak past enemies and loot everything on the first floor will net you the best scimitar in the game (Usuno's Blade), the best bastard sword (Foebane), the second-best darts (Crimson Dart +3, returns when thrown), a Quiver of Plenty (unlimited +1 arrows), a Case of Plenty (unlimited +1 bolts), a Golem Manual (summon a Flesh Golem for 10 rounds each day), an Ammo Belt, a +2 Large Shield, Paladin's Bracers and a +3 Long Bow. This gear is also good enough to get you through Amn, if not further. If that's not enough, one of the adventurers outside the Keep sells the best crossbow in the game, Firetooth.
With a little luck, you can get the lich in the Dancing Crane to waste its spells. Send a single character with a Cloak of Non-Detection and some invisibility item in first. Wait until the lich casts Time Stop and Meteor Swarm then go invisible and exit the room. Wait around for awhile and the lich's protective spells will expire making him killable even for an unleveled party. Aside from the nice XP (no lich in the game gives less than 22,000), the lich's loot includes Daystar, a sword that lets you cast Sunbeam, a high level spell which nukes Undead en masse...and Undead are among the most common enemies in the game.
There is an incredibly easy exploit one can use to get more or less infinite money using nothing but a potion and a gem. First, go into your inventory and drink a potion that isn't in a quickslot. Then, without leaving the inventory screen, swap the potion with a single gemstone. Leave the inventory and unpause. Your character will appear to use an item, but nothing will happen. If you go back into your inventory, you'll notice the "1" in the gem's icon has disappeared. Do the process again and the game's math engine will have an aneurysm. You can now sell your sixty five thousand (!!!) gems for more money than you could ever possibly spend. Enjoy.