One Word Animation - Feedback/Adding Sound

Feedback from showing my animation so far in class on Thursday was to first of all get it to a finished state, then go back and edit by creating more of a flow between each season, work on the transitions between different effects.
I fully agree with this that I need to refine down my work so far to create a much more graceful piece as it is rather clumsy at the moment, hopefully this can all be fixed in editing.
 
I am finding adding soundscapes to my animation extremely difficult!! Because my piece has quite a fast pace and quite a lot of separate soundscapes, trying to get the timing of each piece is very fiddly and hard to do without is overlapping onto the wrong season. I also have not yet worked out how to properly fade in/out sounds so will need to learn this as otherwise sounds cut in and out to abruptly.

The website am have found most of my sounds off is http://www.freesfx.co.uk (full list of references still to come)

I have also decided to try make some sound effects of my own. Although alot of my sounds are from nature (eg. wind blowing or birds singing) so are very hard to make myself, I have a couple that I would like to attempt make myself, just to see if I can and also see what I find easier to work/more computable with flash.