The elemental flight you choose reflects the eye colour of dragons born in your lair. You also get a dedicated forum for your flight members only, and the flights fight for dominance every week.
... but really pick for your favourite eye colour, favourite lore, or both.
Type of dragon you choose as your first doesn't really matter. Pick your favourite of the four. Your lair will be filled with dragons of your choice before long anyway.
I think that's it. Read this!
http://hubpages.com/hub/Flight-Rising-Tips-and-Tricks-for-Beginners