See, for example, the Wikipedia article on poker hands
Jackpot seems heavily weighted in the players favor, as getting a pair of jacks or better is quite common. It also likes setting up flushes and two pair. Depending on how much money I have, I start at about $25 until I hit either a run of two pairs or a flush, then increase the bet by 5. Unless you get a pair on your first hand, prioritize face cards, as these will have a greater chance of not losing money if paired. If you see four cards of the same suit, you can attempt a flush.