I usually do things like these by emulating the way they're manufactured; start with a cylindrical blank, then do a swept cut with the flute Profile along a helical Path as the master flute, then circular pattern that the required number of times. Once you get that right, do the Flute runout and add that to the pattern and then do the same for the end cutting edges and relief. It will help a lot to have an actual end mill in hand (the larger the better) to inspect the profiles, lip angles and the way the flutes end.
As a starter you could try a search for Endmill in the "User Library" on 3D ContentCentral and download a model to see how they did it and if it's any better than your attempts. There may be some in the suppliers section, or 3D models downloads on manufacturer's web sites although these may not be native SolidWorks files.
Trevor Clarke. (R & D) Scientific Instruments.Somerset. UK
