After everyone has his three cards, there is a forced bet. The rules about who makes this bet vary. In most games, the player showing the LOWEST card must make this forced bet, which is called the "bring-in". In some casinos, the rule is that the highest card must start the betting. After the first round, the highest hand always starts the action (by betting or checking).
As a result of this rule about the lowest or highest hand starting the betting action, the advantage of position can change quickly in stud. In hold'em, the person holding the button knows he will have the advantage of acting last throughout a hand. In stud, the person sitting just behind the first actor for one round won't necessarily be sitting behind the first actor on the other rounds. We'll see an example of this shortly.
The moment of deciding who starts the betting action is the ONLY time in poker where suits (spades, hearts, diamonds, and clubs) matter. If two players tie for the lowest showing card (for example, if one shows the Two of hearts (2h) and another shows the Two of clubs (2c), the player with the 2c is considered to have the lower card and would start the betting.
The "ranking" of suits for this purpose is: