I'm FAR from an expert but based on my limited experience I think you're doing great.
Size of the clumps of deer hair are dependant upon the body/ head you are trying to build. If you need to make something really large on one side (like a Dahlberg Diver) I use a large clump on top, take two loose wraps and pull tight (using my fingers to prevent the spin) to keep the majority on top. Then pull the thread to the front of the bunch, throw in a 1/2 hitch or two, a little glue and do it all over again with a smaller bunch for the bottom.
Same thing for seperating colors.
Hope this makes sense.