In a sense radagast's alliance is quite straight forward as there aren't really a lot of options.
Beorn is a combat beast, Radagast is a decent caster who can heal friends or immobilise enemies, on his sleigh his combat ability increases dramatically. Bard is a decent archer.
Eagles are fast moving monsters.
if your having difficulty working out what you want maybe break it down into 500pts first and then go from there.
If I was starting from scratch and wanted to do a pure radagast's alliance force I'd start with Either Radagast on Sleigh or Beorn, then Gwaihir and Two eagles.
With radagast that comes to 500pts on the dot, I think Beron puts it on 505 though.
Ultimately its up to you what you want to include though, at 1000 there's no reason you couldn't include Beorn, radagast, Bard, Gwahir and a few eagles.
But remember you can also ally with other forces too if you want something different.
1000pts is quite big for lotr, perhaps start with something smaller until you've got to grips with it.
