5 Kings
5 Jacks
4 Ten
4 Nine
4 Eight
4 Seven
4 Six
The basic strategy is to only ever use 3 cards to make a caravan, and to threaten a "potential" 26 either by playing 10-6, 10-8, or 9-8. A potential caravan is almost better than a made one, because this frees up your actions and gives you the ability to control the flow of the entire match.
The 5 jack's are very important, the jack is a "broken" card in this game, in the sense that if we both are playing the same deck, then the player who draws more jacks will win most of the time (assuming both players play optimally). Apparently the computer has no clue how to play Caravan, since they typically play jacks on their own cards, which is so bad. The best time to play jack is on an opponents king, since then you get a 2-1 card advantage, and if you can knock them down by more than 10 points, this also gives you a 2-1 time advantage because while your opponent spends their next two turns replacing what you destroyed, you can go ahead and play cards elsewhere on the board. The jack has several other important uses.
It would be nice if the computer had a better AI for this game, and if they used better decks. Against a strong opponent, the suit composition of the deck would be important, as well as the strategy involved in playing your hand according to suits. I think I could pretty easily state some basic principle's that would make the AI a lot stronger, in case any one cares enough to make a mod.