I often use them as a screen for cavalry or the Swordsmasters. I use the High Elf Archers as a normal missile unit or sometimes as a screen for the Bolt Throwers as well as a missile unit. This depends on terrain. At a pinch I'll set up the archers in two units of six, so as to provide a better screen. I'd like to have taken some chariots, but I'm so bad at using them that I'm just not willing to muck them up again.
Chariots are also rather terrain dependent.
This is good news for the High Elves, who cannot defeat certain enemy units without magic help and a total power card. This is the reason that the army above features not very many units, and the ones there are are either powerful or very expendable. I would greatly appreciate any comments or suggestions about this army.