Make your squad's arena of choice the smaller arena.
But, like I said before, if one or two squads do the logical thing, everyone will want to go where they are because, suddenly, the less populated arena isn't the less populated arena any more.
wrongway
There's the problem of the faint-hope clause (variable arena capacities) mitigating against that. I'd rather see fixed arena caps - it would take awhile for the player base to get used to the idea but it would promote the idea of players and squadrons establishing home arenas better than the current system. I don't see HTC doing this at any point in the near future, so blue will remain to a large degree the transient camp where players hold while waiting for a slot in orange to open up.
I think for the most part that the arena caps system works as HTC wants it to, but it is badly presented IMO. At first glance the ratios on the arenas screen can appear nonsensical and confusing, and that really should be fixed. I think just showing the remaining available slots in the arena or showing "Full" when it's at capacity rather than the ratios would likely be a better way to go.
my $0.02
asw