I just started playing and I am having a hard time finding people who play caravan, I know I saw my friend play it and he found some NPC that pulled a gun on him, then gave him a "starter" deck and a holotape on how to play it, I'm curious where that location is, and also any other NPC characters that play caravan. I'm avoiding buying a strategy guide right now until I complete the game on my own, but I really want to get some easy caps from gambling. Thanks!

SPOILERS:
He's in the abandoned gas station in Goodsprings.

Caravan players I know of off the top of my head:
Nash in Primm
Bartender lady in the NCR outpost to the far southest corner of the world map
No-Bark in Novac

There are a bunch more but I've forgotten.

Thanks everyone, I was getting frustrated playing blackjack and roulette with low gambling skill!

Are there differences in skill levels between NPC's? Does the game start you out playing against easy opponents and then increase the difficulty as you gain experience, or is it directly linked to your character level or gambling skill?

Ringo (Goodsprings, then later at Crimson Caravan Company

Lacey (Mojave Outpost)

Johnson Nash (Primm)

Cliff Briscoe (Novac)

No-Bark (Novac)

Quartermaster Mayes (Camp Forlorn Hope)

Dale Barton (The Fort)

Ambassador Dennis Crocker (NCR Embassy)

Private Jake Erwin (NCR Embassy)

Jules (North Vegas Square)

Keith (Aerotech Office Park)

Isaac (often hangs around Gun Runners)

Little Buster (Camp McCarran)

No idea if there are differences in skill levels, however this video tells you how to win everytime (worked for me, I've won all 40 of my games so far):

http://www.youtube.com/watch?v=AorCJkgie_s

i always play with the ambassador

I prefer Lacey and Cliff, as they sell stuff I need and then I can win my caps back.

http://www.youtube.com/watch?v=Ayb48b-4L5g