raining season

Very beautiful..  A good mixing trick is to gently keep lowering the volume, and notice how the various instruments 'drop out'.  If as you keep lowering the volume, and instrument goes out too early (or fast).  bring the volume of the early drop outs.  The fewer the instruments you have, the easier the mix is  As you use larger arrangements (more parts)  mixing becomes more of a challenge.  Try a few mixes in one session, with some instruments at a different volume..  Listen the next day.   

A lot of times, I have to remix, changing volume, EQ, panning of instruments, that only becomes obvious to me after a number of listenings.  I sometimes put my DAW on loop, and sit with a pad of paper taking notes.  For me anyways, when I compose, I am being more emotional..  Mixing requires a different 'hat'..  not that of a musician per say..  Your pieces so far, really favor the piano.  And your piano playing is fine..  My observation would be to lower the piano volume a bit, to let the beauty of your voice, and the strings in this piece to shine out.  

You pieces, musicianship, and writing abilities are quite excellent.  Welcome here. 

This is quite lovely as I sit with my coffee on a rainy day.  The steady bass arpeggiation works nicely to evoke a steady rain, and the right hand melody with its starts and stops makes me think of the irregular drips off a roof.  Very nice!