In case you were wondering just how much J.R.R. Tolkien put into creating his world, here is an amazing account of the philology of one his Elvish languages. Tolkien followed Grimm's phonetic laws. If you look carefully at his work, you can learn how words in Quenya mutate into Sindarin words. This is the equivalent of the verb "essen" in German becoming "eten" in Dutch or "eat" in English.
If you revere Tolkien's work, I think you might enjoy reading this research by Helge Kåre Fauskanger.
Sindarin - The Noble Tongue
More of Fauskanger's work on the languages of Tolkien can be found here.