As with most high-low split games you want to have been dealt a hand that gives multiple possibilities of winning so combining elements of good starting low and high hands gives you the best shot. For example 4 card flushes with the ace and at least 2 other low cards or 4 cards to a low straight. Draws to high only hands often fall through, so having hole cards with both high and low potential is important in Pyramid Steps.
When playing for the low hand the more low cards you have the more opportunities you have to make a good hand. With 4 low cards you are able to use all 3 levels to make your hand. If you have 3 low cards only the middle 2 cards and bottom 3 cards will give you a shot at low. With just 2 low cards, even A2, you will need to hit the 3 card bottom row perfectly to make a good hand. Any 4 cards of 6 or better is definitely worth playing. Any 3 card 4-low or better is also playable. 5-low is probably playable if it is 52A or 53A rather than 543 or 542. With a 3 card holding you are hoping the top single card is a big one. With just a 2 card low, even 2A, you have to hope that both the top single card and middle 2 cards include cards higher in rank than the highest card in the 3 card bottom row as well as not matching one of your low cards. That is a lot to hope for.
The best high starting hand you could hope for is 4 of a kind. You have what is almost assuredly the best hand right from the start. The board can neither improve or counterfeit your quads, but could (very rarely) give another player a bigger hand. But, that is such a far off possibility that it should not concern you. Four to a straight flush (also rare) gives you a decent number of outs using the single top card. (2% to make the straight flush if inside, 4% if open ended; about 17% each to make a regular flush or straight.)
When you have a 4 card drawing hand to a straight or flush they often look better that they actually are. Under most circumstances you realistically only have one draw using the top single card and you will miss it 4 times out of 5. When you don't hit that draw your chances decrease dramatically when using the 2nd row (4%) and plummet using the bottom row (1%).
Trips in your hand is decent, but your draws to bigger hands are also low. (2% to quads with top single card plus 4% with the 2 middle cards; 6% that the 2 middle cards pair to make you a full house.) Big trips might win unimproved if the board cards are not coordinated and there is little betting. (Best chance is in a high-low game where you hope it is the low hand that is betting.) Even then, it is difficult to trust them. Two pair is just OK, but it is also most likely to be helped only by the single top card (8% chance to make full house). Two pair that includes 3 low cards is better. With a single pair or less you are reduced to hoping for lightning to strike in the 2 middle cards or 3 bottom ones.