Drawing Hands
When you're drawing to straights and flushes, even with three good cards in your starting hand you will fail to make the hand you're after more often than you'll make it. Therefore, to make these kinds of hands profitable you are best drawing to them in pots where you still have at least two or three opponents playing.
The more people who are contributing to the pot, the better the pot odds you are getting to continue to draw to your hand. If you are just up against one player and he clearly has a pair or more then you are only going to be getting two-to-one odds on your draw, when the chances of you hitting that straight or flush are much higher than that.
Unless you're in a single table or multi-table tournament, and need to act because of the increasing ante and bet sizes, it is seldom a long term profitable practice to be chasing flushes and draws against just one opponent.
Slow Playing
Because you have two hidden hole cards to begin with in 7-Card Stud there are great chances to deceive your opponents about the strength of your hand. If you have three of a kind, or a hidden high pair, you can engage in some very profitable slow-play against an opponent who clearly thinks they're beating you. The same goes for straights and flushes, especially if you were playing passively to begin with. Opponents never really believe that you've got a flush if you've only got three of the suit showing and the other two are hidden.
As in all forms of poker, the danger of slow-playing is that you give your opponents free cards with which to improve their own hands. For that reason, slow-playing is not recommended if you can sense any danger to your hand, in the form of flushes, straights and high three of a kind hands. If you've got a very strong hand and nothing obvious is out there to beat you then slow-playing is okay, but otherwise you are usually better off if you bet your good hands.
One thing to remember if you do have a really big hand is that you don't want to chase away your opponents before the 5th Street, when the bets double in size. If you're absolutely confident that you have a huge hand then you need to keep someone in to pay you off in the latter rounds, when there's more money to be won.
Bluffing
In low stakes games of 7-Card Stud you may well be wasting your time to try and bluff an opponent. Many inexperienced 7-Card Stud players see it as primarily being a drawing game and will want to get every last card they can before they decide whether or not to give up on their hand. If the stakes are low then they will just keep calling until the river.
The same kind of Fish, Calling Stations and aggressive players you find in Texas Hold'em will still be there in games of 7-Card Stud. Always try to identify what kind of players you're up against when deciding if it's worth bluffing or not.
If you're playing at higher levels, or in a game against players who know what they're doing then bluffing can be carried out very well in 7-Card Stud. If your upturned cards show a pair then there is no harm in trying a bet or raise to tell everyone that you've now got three of a kind, regardless of what your hidden hole cards actually are. If you get called or re-raised then you'll know that your opponent either does have a very good hand or is at least drawing to one.
One very powerful bluff in 7-Card Stud can be when your four upturned cards show that you have four of the same suit or four cards towards a straight, even if you don't have the other card needed in your two face down hole cards. In these circumstances you can bet aggressively, as your opponents will have to fear that you have the flush or the straight and may well fold.
If you do get called then you still have one more card to draw which could actually complete your hand. If get re-raised then your opponent is either testing your mettle or actually has a big hand or a draw towards one! Look at their cards and try to work out what they could be playing back at you.
Folding Hands
No matter how good your starting cards might have been you should always be prepared to fold when it becomes apparent that you've been overtaken by a better hand. Unless you have a good draw to a strong hand don't be afraid to muck your cards, instead of chasing long-shot outs. Chips you don't throw away by chasing unrealistic hands are worth every bit as much as the ones you have to try and win back when you've lost a big pot on an unsuccessful chase.
Good players will always recognise when they're behind and unlikely to win a hand and they'll muck their cards instead of losing chips by blindly chasing a hand they're unlikely to hit. They'll also know when it is they who are being slow-played and will not be afraid to muck their cards.