If you don't wanna look at a how-to guide, the game actually does explain how to play via a note given to you. The objective is to get each stack on your side to 26. SUITS DON'T MATTER, JUST COLOR. You can do this by either walking "up", meaning building your stack from 1-10 (ideally you don't wanna take big jumps between numbers if avoidable unless you have a deck built to play a certain way like a lame nerd), or you can also walk "down", stacking backwards from 10-1 (the same about big jumps is true this way as well.)

Just about any trader in the Mojave will have a card or two you can buy from them, usually for about two caps per card. It really doesn't matter if you do or don't buy them, as you can win just about anything with the default standard deck. That being said, it doesn't really hurt to buy them, especially if you want to build one of the try hard decks.

Kings placed on any number card double that numbers value on the pile. Kings placed on other kings double that doubled value. (Example: If a stack has just a 6, playing a king on the 6 raises that stacks' total to 12. Playing another king on that stack would bring that stacks' total to 24. NOTE: this means a king on the other king, don't try to place like an ace to make it 13 and then another king, that would only double the ace and make your total 14.)

Be careful if relying on kings to hit 26, because a jack played on a king will remove both the king and the number they were played upon. Note that if kings are stacked like in the above example, they will continue to remove kings and the first number a king was played upon in the pile. Using the above example pile of 6, king, king to be at 24, if a jack was played it would remove BOTH kings AS WELL AS the 6, leaving you with 0.

Note as well, you can play kings on your opponent's stacks as well, which if played correctly will usually result in them scrapping their piles altogether. (The A.I.'s aren't usually smart enough to just remove your kings, but it has happened before.)

Queens are great for people not using a constructed deck that rely on 10's, 6's, 8's, and Kings because they allow you to change the way your cards are walking. For example, if you started a pile walking "down" (going 10-1) and played a stack that went 10, 6, 4,1 for a total of 21, and had a 5 in hand, you can then play a queen and play your 5, as you switched the way your cards were walking and built in the direction of 1-10. Note this is a watered down explanation and there's sometimes exclusions due to suits/colors but the general wisdom is sound.

Jacks are essentially a delete card, removing the last number card on a stack from play. As covered in the "Face Cards: Kings" section of this guide, a jack played on a king removes not only the king but any other kings stacked on top of the stack until the last number played on the pile is removed. If you need a better example, please check the "Face Cards: Kings" section.

Jacks are also allowed to be played on BOTH sides of the playing area, meaning you can get rid of your opponent's cards as well as your own if you so choose. I recommend holding onto your jacks until it feels like the opponent has expended all of theirs unless they are close to a full caravan before you, as you can usually bully the A.I. with simple logic and counting.

Jokers are a bit goofy. They have different effects depending on if you play them against an Ace, or 2-10.

Playing against an Ace, it will remove all other non-face cards of the ace's suit from the table. So, if you place it against an Ace of spades, any other cards on the table that are spades, except Aces or face cards, will be removed. So say you have a two of spades, a five of spades, and a King of spades on your side, and your opponent has an Ace of spades, a three of spades, and a ten of spades, all the numbered ones will be removed, leaving your Ace and King of spades, and your opponent's Ace of spades.
If it's played against a numbered card, then it'll remove all other cards of that value from the table. So if you play it against a two of clubs, you'll keep that two of clubs, but all other twos on the table, both your's and your opponent's, will be removed.

(Thanks for the reminder Dan, these were so rare in my games I didn't even think they'd matter enough to explain, but a guide is a guide.)

Most people who look at this guide probably want to play it for the achievement, in which case, I feel they would want to know who they can milk the most cash out of with this game. The two highest rollers who play caravan are the NCR Ambassador Dennis Crocker, who resides in the embassy on the strip, and No-Bark, the crackpot who lives in a shack next to the hotel in Novac. Each time you win, they will bet less and less, but you aren't here to make friends, so break their banks and their spirits. Especially Crocker's.

Note that despite me making a section listing only these two NPC's, there are a bunch who you can play Caravan against. These are just the two with the biggest billfolds, and since money is nice, they got an honorable mention.

There is a challenge to LOSE five games of caravan. Note that your 30 wins for the achievement do NOT need to be consecutive, so I recommend beating someone who you have a pretty solid handle on beating and beat them until they're only willing to bet a few caps. I did this with Ringo after saving him in Goodsprings, but you can really do it to whoever. Once they've been thoroughly rinsed and are in that spot of only willing to bet a cap or two, just match wager and lose. Stack your cards to whatever ridiculous number, throw away all your cards, do whatever. Since you have to win 30 times, you should have plenty of opportunity to take small losses, and if you choose to throw money away and lose big, that is entirely your own fault.

I don't have more help for you. Get ♥♥♥♥♥♥.