I've done the first nineteen bars of a sonata in Bm and I'd love for some constructive criticism. I've added basic dynamics, although in the final product there will be many more.

Remember, this is more or less a sketch of what the final will be. I'm just new to composing so I want some help if it's possible.
I've got a couple quite good pieces that I've written on the piano....but I need to take the time to figure out how to notate them. That's something that I'll need to take some time doing. ha.

But, back to this piece. Here are links to the Midi and the Pdf file of the sheets.
http://www.4shared.com/file/72476932/a8852ff/Sonata_in_Bm.html
http://www.4shared.com/file/72476935/94ecc75c/Sonata_in_Bm.html

Constructive criticism will be greatly appreciated. I think this piece has potential to be good, but it'll need to be revised.
Oh, and I'll start learning this on piano once it's done to supply a real recording....but the way the midi plays it is totally wrong as far as dynamics and emotion goes. But then again, midi's usually are messed on those things.

I'd clarify the harmonic structure a bit. It starts off in b minor and wanders off a bit loosely. I'd personally like to see a clearer path to the second thematic area, both in terms of harmony and texture.

Do you have sketches for the 2nd key/theme area yet?

No, what I posted here is everything I have so far. And I'll play with the harmonic structure some, but some of the wanderings were intentional as either secondary dominates or modulations.
I'll need to get a good theme going that I can do variations on too. haha.

A sonata will typically have one modulation in the exposition. Even pieces as harmonically unstable as the Berg or late Scriabin sonatas still limit themselves to two stable areas. Otherwise, it doesn't really fit the philosophy of a sonata.

Hey, I have a sketch up through the development.
I took the part that you said was wandering harmonically and made it into a development. Remember, this is just a sketch

http://www.4shared.com/file/72858992/1dba5e5d/_2__Sonata_in_Bm.html
http://www.4shared.com/file/72858995/83decbfe/_2__Sonata_in_Bm.html

Again, here's a midi and PDF

Good! That makes more sense to me now.

The next thing I'd suggest would be to clarify the phrasing. I have a hard time knowing where the phrases begin and end.

For example, the first two measures are a clear phrases. The next two measures are also clearly a phrase and provide symmetry and an answer to the first.

The strange thing is that the second phrase ends on a second inversion chord, which is considered unstable and is almost always followed by a cadence. The stronger tonic comes a bar later on beat 3 - a weak beat.

In other words, the first section sounds like it has two endings - a weak harmony on a strong beat (measure 5) and a strong harmony on a weak beat (3rd beat of measure 6.)

To further confuse things, the next phrase, beginning in measure 7, starts with a ritard. To my ears, that's very confusing. We get a sense of stop (measure 5 beat 1), stop again (measure 6 beat 3), and then slow down. It doesn't feel natural.

I mention this because your music is somewhat similar to Hindemith's writing. He was able to get away with adventurous or ambiguous harmonic structures because his phrasing and structure is extremely clear and regular - lots of four measure phrases with easily identifiable cadences. Check out the 2nd piano sonata for an example of what I mean.

I hope that makes some sense - keep writing!

Ah yes, phrasing was something I hadn't really thought of. Thanks for the tips there, I'll through and mark my phrases clearly and perhaps change that some stuff around to clarify phrasing, like that second inversion I chord to a first inversion. And the Rit. was already something I was thinking of taking out, but I just hadn't decided for sure if I wanted it there or not.

And I've never heard of Hindermith, I'll look at his sonata to see what you mean. Thanks!
And if you couldn't tell, halfway through the exposition I modulate to D major, stay in D until the beginning of the Development, and then wander around between a few keys only to end up back in Bm.

I saw that...the exposition should end in D Major, though. The idea behind a sonata is that you begin in tonic and move away in the exposition, remain in tonic during the recapitulation.

the exposition does end in D Major....
The final chord is a D which leads into my development.

Oops! Then all is well.

Hopefully I'll have time tomorrow night or at least sometime this week to work on the recap and ending.