When you compare two players with a straight, the straight with the highest card in it wins. Three of a Kind - Three cards of the same rank. Pair - Two cards of the same rank. Highest Card - If there is nothing better, the highest card wins. If there is more than one player with the same hand, the five highest cards that play is the winning hand.
Aces can be high or low.
When involved in split pot games of Omaha or 7 Card Stud, straights and flushes do not count against you for low hand. For example, the best low hand possible is 5,4,3,2,A. It would be the same strength hand for the low half of the pot whether it was mixed suits or of the same suit. If the highest card is common when comparing the strength of two hands, then you will continue to evaluate the next highest card on down until a winner is determined.