Try alkaline extraction method ( water at pH 8)

Just homogenate the tissue with buffer and do acetone precipitate for over night at cold condition. dont go for ammonium sulphate precipitation..

I would adapt the buffer to the type of protein (membrane, mitochondrial, nuclear, etc.)you need to extract, and centrifuge to further fractionnate (soluble, insoluble, organelles etc.) But definitely I would use a good homogenizer like those from Precellys or Bertin (see link below)

http://www.precellys.com/