don't clap between movements
Well.....surprisingly, Freakyfemme The Music Snob is willing to forgive this. Why? Because almost every piece I've ever played (with the possible exception of the Saint-Saens Sonata for Clarinet and Piano, which I played in first year, and *maybe* the Hindemith Sonata I played last year), consists of a really big, splashy first movement that's more virtuosic than the others, one or two more "lyrical" inner movements (think Adagio or Allegretto--they're nothing to sneeze at interpretation-wise, but they're still not as technically difficult, and therefore they aren't as impressive), and then a pretty Rondo movement to finish it off, which is still less difficult than the first movement, because there's so much repetition involved. So, often, it's tempting for people to want to applaud after the first movement, because that's almost always the real "crowd-pleaser" movement, and sometimes I appreciate it, because first movements are always nerve-wracking. So, if someone forgets themselves and claps after the first movement, I don't think, "what an uncultured boor," I think "hey cool, looks like my fingers are co-operating with me," lol. If they clap after a middle movement, I think "hey, that means I have good interpretation." So, I'd rather play for an audience full of "unsophisticated" between-movement applauders than one full of "cultured" individuals who cough, sneeze, sneer, talk on their cell phones or to one another, or leave mid-performance.
By the way.....that brings me to another "rule." If you're going to a shared recital (as in, one person does the first half, then the second person does the second half after intermission), then please, either go to the whole thing, or skip it altogether. This isn't *as* important in the case of a professional concert that's well-attended, where you won't be missed, but for a student concert, it's sort of an "empathy" thing, or at least it is from my point of view, since I've been on the other side of that stage many, MANY times, but I can see how non-music people might not see it that way. I didn't have this problem last year (i.e. the "mass exodus at intermission" problem), since I did a full recital (well, almost full, it was about 45 minutes), but I felt really badly for my friends who did. It must be so disconcerting to get all psyched up for a solo recital, especially if it's your first, only to have half the audience clear out after your "recital buddy" finishes performing. Unfortunately, that happened to Princess Flutezilla, and the offenders were, surprisingly, the Rez Gods. They came to see the girl who was playing in the first half, and it was unfortunate for them, since Princess Flutezilla is one *hell* of a musician, and she'd prepared an awesome second half. But, they mentioned Other Girl a week or two ago, which gave me a chance to gently advise them that, in the event that they wish to attend another student's shared recital (Other Girl will either be doing a full one this year, or not at all), then they should really stay for both halves.