Position

In seven card stud your position can change with each card dealt. As it is with all forms of poker the best position is to be last to act in a betting round so you can use all the information about how many people are staying in the hand and all the bet and raise action before it is your turn to act. There's a built in counterbalance in stud, though, that after the bring-in (the lowest card has to put out a fractional bet to start the action), the highest hand showing always has to start the action, or in short, be in the worst position. The action then proceeds clockwise around the table so the person sitting to the immediate left of the highest hand is the last to act during a betting round (the best position) then another card is dealt and the first person to act potentially changes if someone else gets a higher visible hand.

Here's an example for those new to 7 card stud. The cards are dealt:

Player 1 Player 2 Player 3
Back of Card Back of Card Three of Clubs
Hole Cards Up Card
Back of Card Back of Card Ace of Spades
Hole Cards Up Card
Back of Card Back of Card Jack of Clubs
Hole Cards Up Card

Because the 3 of clubs is the lowest card on the board Seat 1 must post the bring in bet, let's say $1.

Player 1 Player 2 Player 3
Back of Card Back of Card Three of Clubs Three of Diamonds
Hole Cards Up Card 4th Street
Back of Card Back of Card Ace of Spades Five of Spades
Hole Cards Up Card 4th Street
Back of Card Back of Card Jack of Clubs Jack of Diamonds
Hole Cards Up Card 4th Street

Now the highest hand on the board is seat 3 who has a pair of jacks. They must start the action. Also because they have a pair showing they have the option of starting the betting with a double sized bet on fourth street (the fourth card dealt). After they act then seat 1 acts and finally seat 2 acts.