Having said that, the first book I want to advise against reading is the Rudder. This well-known collection of Orthodox canon law is noteworthy--if you're at all familiar with the field in Roman Catholicism--for its outlandish brevity. Even so, it contains very little that is of any direct use to a layman. Perhaps most importantly, canon must always be handled with economy. Knowing the rule is certainly useful; but knowing the rule without knowing how and when to apply it is dangerous. In practice, many of these rules are relaxed in various ways and at various times. We might quibble over cases where perhaps the rules are relaxed too far (though speaking for myself, I have absolutely no basis from which to quibble), but it is axiomatic in Orthodox canon law that economy plays a critical role. Economy is the domain of clergy, and the specific application of canons is best left to their discretion. A layman is ill-equipped to do much of anything beneficial to himself or anyone else in this area.
That much I knew before I ever tried to read the Rudder, which is actually why I felt safe carrying out the project I assigned myself. I had no serious expectation that I would end up with a bunch of new rules to follow. I just wanted to satisfy my curiosity about the contents of the book, particularly how much would have any bearing on someone who's not a monk or cleric. The simple answer is--very little. Most of the canons have to do with things like the appointment, movements, and discipline of clergy and monastics. Of those that don't, two large categories remain--established penalties for various types of sin (which should be applied by a confessor, not by an individual to himself), and statements about doctrine, heresy, and how to resolve schisms. The theological statements may be of some general use, but their contents are repeated in so many places--and often much more clearly and completely--that it hardly bears recommendation as a key source for learning Orthodox doctrine. Even what one might glean from the canons about discipline, since they incidentally identify various types of sin, is probably not worth the trouble. There are plenty of guides for confession, any of which would contain a more or less effective list of sins. The Rudder is not organized as a confession guide, so it's best not used as one. Indeed, if that's what you're looking for, the Exomologetarion would be a much handier tool, and it's still probably in at least the debatable category for lay use.
I might add that most of the sins listed are so straightforward in Scripture that they need no special comment as sins. Again, the point of the canons is to address the means of discipline, not identify the sin as such. As I was skimming through, I found only a handful of offenses that I wouldn't have picked up from a general familiarity with biblical morality. I repeat them here as the minuscule produce of several hundred pages:
- Several canons order discipline for participation in or viewing of dramatic entertainment. I can't say myself whether this would apply directly to the kind of entertainment that is popular today, or if there was a more explicitly pagan component at that time. Of course, there are plenty of good reasons to think very carefully about the visual entertainment one consumes.
- In a few different places, there are canons indicating that Bright Week (the week after Pascha) should be observed by refraining from work and spending as much time as possible in church. I don't know of any church these days where enough services would be offered (perhaps in a monastery), but it's probably not a bad principle to apply generally, if one can actually spare the time off of work.
- In a few places, the importance of Sunday is emphasized. Notably, one should not travel unnecessarily on Sunday, nor should one skip three consecutive Sundays in church without a compelling reason. The latter is pretty straightforward as a general rule; the former is a beautiful continuation of the Jewish Sabbath observance and one that I think we would do well to take seriously in our lives today.
- Finally, I found at least one reference in passing to the goal for laymen of eating for sustenance, not primarily for pleasure. The main point, if I understand correctly, was to caution against excessive partying; but I thought it was an interesting argument, which I've seen plenty of times in ascetic literature, but I can't recall whether I've seen it applied elsewhere to laymen.