Omaha/8 is a game of scoops (winning both the high and the low) and having a great hand with a redraw to a better hand. Most, if not all, of your starting hand selections need to keep these two things in mind. Another important point is that all four of your hole cards should work together in some way. Ac Kd 3c 4d works well together because you have three low cards and two ways to make a high flush. Ad Kc 8s 5h doesn't work well. Here are some starting hand suggestions. An x denotes any card of any rank. A w denotes a wheel card (2, 3, 4 or 5). A t denotes a trump plus the ten (T, J, Q, K).
[A 2 x x] You must be careful with just an A 2 with no counterfeit protection.
[A 3 x x] If the ace is suited to one of your other cards.
[A w w x] As long as the two wheel cards are not the same, like 4s, 4d)
[w w w w] Four wheel cards, even if you have one pair, but not if you hold two pair or trips.
[A t t t] An ace with three high cards, especially if the ace is suited, is a strong hand, especially if the board doesn’t come up with a possible low.
[t t t t] Four high cards, even with a pair or two pair is also a good high only hand.
The above guidelines are extremely tight and are meant to be used while you are learning the game. As you gain experience and learn your opponents playing styles and hand selection, you will be able to play a few more starting hands. Hands with an A, 3 and two high cards are often playable as well as hands containing an ace suited to one other card that offer straight possibilities and some low potential like Ad 4d 6s 7c.
Just as in limit holdem, pot odds play a major roll in winning at pot limit Omaha 8. The biggest difference is that in O/8 you usually only figure your outs as the ones that make the nuts.
When playing Pot Limit Omaha/8 your goal should be taking your opponents entire stack. This is done by only playing hands with potential to scoop the pot. Remember that often there is no low possible so high only hands can be valuable. Many new players make the mistake of overvaluing big pairs in starting hands. Big pairs must improve in order to win. Also after the flop, made hands with redraws to better hands are the ones that make the most money. In addition, drawing to just a low hand is a quick way to going broke. Especially if the pot is heads up or three handed, even if you hit your low hand you may have to split and if you don't have a chance at high you will lose money.