On my second playthrough I discovered this get rich quick scheme.

Forget about Goodsprings. Go straight to hidden valley and beyond to Niel's shack, then by just entering the corner of Black Mountain you can get through a little ravine into the area south of New Vegas. You will have to do a bit of sneaking and fighting as you are going to be level 1, but it is possible to get through to Vegas without having to fight anything bigger than a Bark Scorpion. In the NV area visit the gun runners and the clinic to stock up on bullets, stimpaks etc trading stuff you have found on the way.

Go on to Jacobstown, again sneaking and scavanging opportunistic stuff. Once you get there, take the 2500 caps from Marcus and start a fight with the mercenaries. You should do this from afar and then run off to the sanctuary of Jacobstown while the muties and the mercs duke it out. If the battle goes the right way you can then scavange loads of loot from the corpses for plasma rifles, assault carbines, combat armour, really top stuff for so early in the game. I did this while still on level 2 and ended up disproportionately tough and rich, without having to do very much killing or dying.

Finding or instigating battles has always been an easy (and very satisfying) way to rake it in in the FO games, morally dubious though it may be. Does anyone know any other good opportunites for this (esp possible in the early game)?

You can go straight to the merc camp and pick the mercs off at range or lure them into powder charge/fragmine traps.
That'll give you adv combat armor, the YCS-something and a few smgs.

South of Camp Mccurran, near the Allies Aerotech(?) office where Fiends and NCR fights; there is also the west vegas pump station.

My EW users regularly purge the West Pump Station and South Vegas Ruins of Fiends (it helps that there are multiple quests that send me to the vicinity) for parts and ammo, and anything not needed gets sold off. You can get a Laser RCW and a Plasma Rifle or three early on that way, which makes things a lot easier early on if one is so inclined.

Their loadouts are randomized and you might get conventional firearms as well, which makes them a decent-to-good source of Hunting Rifles and (rarely) Sniper Rifles in the teen levels (you'll know they are carrying one if you start taking chunks of damage while wearing Combat Armor or better).

While I never do this, and it's relatively high-risk for a low-level character, you can try knocking over a merchant caravan. There is an overpass near Wolfhorn Ranch that is used by the traveling merchants, and if you go there early on there will be a party of 4-6 of them (and 2 Brahmin carrying assorted stuff) who will cross the overpass, turn North, and get in a fight with 4 Legion troops nearby (there are also a couple of harvest-able Prickly Pear cacti if one is doing the survivalist thing). I usually let the fight play out and loot the dead, however the caravaneers often carry 1-2 9mm and/or 10mm SMGs so if you are feeling up to it (and are willing to potentially piss off the NCR, since it's their caravan) you can assist the Legion troops and get the SMG(s), a few suits of Leather Armor, possibly a Reinforced Leather or a Metal Armor, and a whole bunch of 9mm and 10mm ammo along with some pistols and whatever the Brahmin are carrying.

If you plan to try that, I highly suggest letting them get into the fight with the Legion so that the Legion troops take the initial salvos, since they can take the abuse fairly well for a little while. Taking a Med-X and possibly some other chems (and you should have some by this point) prior to engaging them yourself may be wise as well, since you need to blitz them, and hard, to avoid getting perforated by multiple auto-weapons. The best haul I've managed off the corpses so far was all 4 sets of Legion gear, their weapons, 2 10mm SMGs (+ammo), 2 sets of Leather Armor, and 1 set of Metal Armor (how they killed the wearer is beyond me, but they managed it), plus a bunch of different ammo and some spare parts from one of the Brahmin (the other one managed to live, somehow), but there were still 4 Mercenary guards left standing so there is the potential for a pretty large payday if you can manage 4+ opponents at once while still only level 4 or so.

Getting Money is my characters middle name.

Jacobstown like you said you can get 2500 or 3000 caps. Thats an ok method but they're better ways to get money.

1. Sneak to the strip and gamble.

Gambling is a very effective method on acquiring cash. This method also helps if you have a high luck. Also buy the Naughty Nightmare in Freeside as that gives you +1 Luck. 1st save before entering a casino then enter the casino give up your weapons then get about 1000 chips. Then save in front of the machine and keep max betting it until you get the 16000 or the 32000 reel. If you run out of caps reload and try again you may have to wait a minute as the Devs turn the machine off for a minute to prevent cheating.

2. Steal, Steal, Steal.

Stealing items is a great way to make cash, Camp Golf is recommended.

3. The 7 Snowglobes

The Snowglobes are worth 2000 a piece and its pretty easy to get all 7 the only two you'll have to worry about is Jacobstown and Nellis for obvious reasons (Giant Missile Shells aren't fun to dodge).

4. The Van Graff Option.

Now I wouldn't reccomend this option if your using the companion Cass but start up the quest with the Van Graffs and when you get to the guy wearing the Barter Outfit let him in and he'll blow himself up and you can claim the Combat Armor and a couple other items in the shop however you won't be able to claim the Energy Weapons because the Devs probably did that to prevent abuse. If you blow up the shop you'll get about 10,000 caps but its 20,000 if you can somehow kill all the Van Graffs without the guy blowing himself up.

I think No 2 is the best option now if your roleplaying a good character just head over towards the Vegas ruin and murder a couple raiders that'll get your karma back up to where it should be.

Step 1: Start with Luck 9
Step 2: Head to Vegas
Step 3: ???
Step 4: Profit.

:rofl:

Best. Misspelling. Ever.

P.S. For getting rich quick, you can steal LOTS of expensive weapons and armor with little effort at the Boomers' Munitions Storage and the Silver Rush. Total worth of what can be taken there is over 50 000 caps, and higher still with good Barter and Repair. It's more than you can win in all the game's casinos combined.

Go to the Legion Raid Camp, ignore the captives and kill the Legion troops, should only be 4 - 5 of them. Once done, you can sell their armor, and weapons for some good bank, plus they respawn after about 2 days.
http://fallout.wikia.com/wiki/Legion_Raid_Camp