I'm a very strong stud player with a lot of experience playing all three of these games professionally for most of my adult life. Stud hi and Stud hi-lo are extremely complex games, much more so than NL Holdem. How you should play each game is extremely dependent on the ante structure with respect to the limits. It's all about stealing correctly on 3rd street in Razz and Stud Hi, and that dictates how everyone else plays as well. Structures that offer 1.5 to 1 or lower on a steal attempt should and often do play very tight on 3rd street. However, structures that offer 2 to 1 or higher on a steal attempt play extremely loose. Those subtle differences are monumental in how you should approach the game. As an example, in the tighter game with lower payoff, you won't want to steal with a hand like (T4)Q in mid position with an Ace behind you, and you won't want to 3bet a hand like (Q7)Q with an Ace or King behind you after someone opens with a Ten, but in the looser, more rewarding ante structure, it is imperative that you raise and 3bet in both of these spots respectively. This has an avalanche effect on how the entire table plays, or at least should. It builds bigger pots, offering better odds to draw at, and increases your variance quite a bit. The best part about Stud games is that there are 3 large betting streets, whereas limit holdem and omaha8 each have 2. This means mistakes are much more costly, and value bets are much more important. I have dozens of poker videos where I play mixed games online that I can send you if you are interested in watching them. But it's pretty difficult to walk someone through what it takes to be a good Stud player on a keyboard. They are extremely complex games.
In Razz, 3rd street is all about how many low cards (8 or lower) are out and how many are behind you and what the structure is. If you have any card 8 or lower face up with only one low card left to act behind you, it is imperative that you raise even if you have KK down. If you have 3 low cards or even a hand like (29)6 and you are the last low card and someone has raised ahead of you who is in steal position (they only have one low card behind them) then you must reraise any good hand unless they are super tight and never steal. If you are in early position with multiple low cards behind you, you can limp or raise any strong hand, occasionally limp reraising. One of the biggest mistakes I see amateurs making is playing hands like (J2)A, (K3)A, (A2)2, etc when there are 3 or more low cards behind them still to act. You will get destroyed if you play 2 card Razz hands from a non-steal position. Also, if you are the bring-in, NEVER defend with a brick in the door (J,Q,K as your upcard). Something that is interesting about Razz is that unlike holdem where defending your blind becomes more attractive as more players enter the pot, the opposite is true in Razz. It is a mistake to defend your bring-in against a steal attempt but it is an even bigger mistake to defend your bring in when there is a raise and a caller despite the fact that you are getting better pot odds. Razz is a very close game odds wise. The better hand is rarely that far ahead, and so raising with thin edges and putting in squeeze play raises even when you know you're in 2nd place in a 3-way pot becomes critical. You don't want to get caught between a squeeze, and your odds of outdrawing two players is much more difficult than the pot odds on offer allow you to overcome. As a general rule of thumb, you only want to play when you have 3 cards 8 or lower to start with, and you usually don't want to raise if your 8 is face up. But that also depends on the dead cards. If you have a hand like (84)6 and you are first to act and behind you are a 2, 3, A, A, J, Q, and a 5, you should just muck it because it's not that strong. But if you have that same (84)6 in a different hand where everyone folds to the player on your right who raises with a 5 in the door and you look to your left and see a 3, T, and the K bring in, you should 3-bet that (84)6 a fair percentage of the time. Also, your hands are stronger when your pair cards are dead - e.g., if you have (56)3 and the cards behind you are A, 3, 5, 5, J, 6, K, you should be prepared to go to war with this hand. I would cap this hand every time on 3rd street if the Ace wanted to get into a raising war. On 4th street, you want to give up if you catch a brick while your opponent catches good unless it was double bet on 3rd street, in which case you can't ever fold on 4th unless you are at least 2 cards behind - fold maybe 875K vs someone who 3bet with (xx)35 on third street, but don't fold 635K in this spot if it was 3bet on 3rd. On 5th street, you can generally call if you are one card behind but not two. These tips will get you started, but 5th, 6th, and 7th street decisions are pretty nuanced and important, as well as costly when misplayed, so you really need a lot more studying if you want to play this game well.
In Stud hi-lo, you can do alright just by playing tight. Never play a card with a dangler in it like A29 even if the A is in the door. Stealing is less important in this game, although you still need to do it occasionally, but playing A29 or A2K is a great way to pay for someone else's new pair of shoes. You want to play hands that coordinate together and that give you a chance at BOTH the high and the low. This can be super strong high hands like QQQ, hoping no one makes a low, or it can be hands like 4d5d6d, As5s7s, AA2s, etc. You pretty much never want to play big pairs in this game (hands like 3KK), expect for a few steal situations. If you see someone raise from early or middle position with a 9 or T in the door, they are either rolled up or a terrible player. Those are the only two options. Don't be that guy. Basically look for three low cards that also have high potential, and avoid tricky spots and you'll do alright. Mastering the game takes a ton of experience though, and again, there is much to learn about how to play the later streets. Look for jelly roll situations (where you have a lock on half the pot and are drawing live to the other half) and get as much money in as possible when you have it. Semi-bluff raise your strong two-way draws when there are 3 or more players in the pot and one of them are clearly going for the high. Put high only hands in tough spots when you have the low. You want them to fold so that you can take it down with a pair of 4s for the high when you are going for the low.