For this tip, I'm going and show how you might improve your play on seventh street.
My first suggestion for playing on seventh street is that you need to look at your pot odds when facing a final bet. When playing $5-$10 Stud, for example, you'll often need to call a $10 river bet while looking at a pot of $70. In this spot, where you're getting 7:1, if you have any suspicion that your hand is good, you really ought to call. The odds are so favorable that throwing away a lot of marginal hands would be a mistake. This is very different from no-limit poker, where you'll need to make some big laydowns late in a hand. If you're making the transition from No-Limit Hold 'em to Limit Stud, keep this very important point in mind.
Some of the tougher decisions on seventh street arise when you're holding one pair. Let's say you start with a pair of 6s and your opponent open-raises with a King as his door card. He bet all the way, representing a pair of Kings, and you called. Neither of you seemed to improve on fourth, fifth or sixth streets, and he bet out on the river.
At this point, you can be fairly certain that he doesn't have a pair of Kings. Most people don't have the heart to bet one pair on the river. So, in this case, you're likely up against something like Kings up, some sort of hidden hand, or a total bluff. Given this range of hands - and knowing that a bluff is a possibility - you should make the final call. You'll pick off a bluff enough of the time to make the call profitable.
I want to point out here that, since it's proper to call with a lot of marginal hands, betting with one solid pair on the river is often a good idea. If you start with something like a pair of Kings and your opponent doesn't seem to catch anything, don't be timid on the river. Oftentimes, you should bet, knowing that a lesser hand is likely to call.
Now, let's look at another river situation. Let's say that after the river has been dealt, you have Q 10 9 8 with three clubs showing. You made a straight on the river after your opponent has been aggressively betting his hand the entire way, showing Ad Kd 9s 6h.
After betting into your hand on sixth street, he again bets into your hand on seveth street. In this situation, you have to think about what your opponent is betting into. Most players will not bet into such a scary board with one pair or even two pair.
We have to assume that our opponent is either bluffing with a weak hand and is unconcerned with our hand, or has a huge hidden hand and is hoping to get three bets on the river. This could be a situation where you might just call, especially if there is a third hand behind you who might over-call with a marginal hand that he would fold if you had raised.
When playing Limit Stud, be sure that you're making enough value bets and crying calls on the river. Keep the pot odds in mind and you're likely to make the right play.