Blue fire and quake, sonic and quake. Most successfully with blue fire and quake, I have two moon dragons from this combination but also got a sun dragon from them.
I would be tempted to say moon comes from rainbow and water type and sun would be rainbow and fire type. I say this but Im not sure if you can even breed a rainbow dragon as I don't have I yet! Sorry...
From baby to normal do a titan quest,for normal to bigger buy dragon chow,you can get the REALLY special dragon chow from some missions(Eg.Extra Credit)
Go to lady Celestia and feed you dragon(you need to buy food) then click train your dragon. If you have a dragon amulet you can do it anywhere by clicking on the dragon amulet.