Many Elvish Tongues
"Elvish" is a broad term for the numerous Elven languages. The languages started out as one language, which is often referred to by Tolkien-language enthusiasts as "Primitive Elvish" but over the millenia of separation - the language fractured into many languages: Avarin, Nandorin, Lindarin, Sindarin, Mithren, Falathren, Telerin and Quenya. Middle-earth is home to the majority of these languages.
Out of all of these vibrant and varying tongues, Tolkien put most of his effort into two of the languages: Sindarin and Quenya, even going as far as to develop different dialects of them! (Sindarin has four dialects: Doriathren, Exilic, Númenórean/Gondorian, and Woodelven; Quenya has three: Vanyarin, Númenórean, and Exilic. Of these, the dialects of Doriath and the Vanyar are considered the most "pure": the others being influenced by learning them as second languages.
By the Third Age, Sindarin had become the Elven Lingua Franca of Middle-earth. That doesn't mean that it had completely replaced the other Elven languages, but it was used as a second language by many Elves of Middle-earth.
Quenya isn't used much in Middle-earth. You can find it in Kingly names of Númenórean and later, Gondorian rulers, and it is spoken by Exiles to other Exiles, (Exiles being Noldor who returned to Middle-earth, exiling themselves from Valinor). Quenya is the language in majority in Valinor - though it shares the land with Telerin and Valarin - the language of the Valar.
If you were to meet an Elf in Middle-earth, it's safest to start speaking in Sindarin. If you are in Valinor, it's better to start greeting them in Quenya.
Pronunciation
I use IPA (International Phonetic Alphabet) to show the pronunciation of words and phrases, because it is the most accurate way to describe the pronunciation of the phrases. IPA is mostly based on the Latin alphabet, like our own writing system. Even though there is a lot of overlap, there may be several symbols that you may be unfamiliar with. I shall describe those for you.
Miscellaneous Letters
The /slashes/ are used to indicate a type of phonetic transcription, in this case, not quite surface form (exact pronunciation), but close, as we can never be 100% sure of how the languages would be spoken. Surface form would be written in [brackets].
Periods are used to show syllable boundaries.
‹ˈ› is used to show primary stress - a syllable said louder than other syllables. It goes directly before the syllable it is marking.
‹ˌ› is used to show secondary stress - a syllable said louder than other syllables, but not as loud as the primary stress. It goes directly before the syllable it is marking.
‹:› is used to mark long length, as in "the duration of time that the sound is said". This mark will be placed after a vowel to show that it is said longer than normal. The same is achieved in consonants by simply doubling the consonant.
‹ˑ› is like ‹:›, but half as long. You'll see this symbol appear in Sindarin transcriptions only, as Sindarin words have three different vowel lengths!
Vowels
‹a› is like the A in "father".
‹ɛ› is like the E in "bet".
‹e› is like the A in "bait".
‹i› is like the I in "machine".
‹o› is like the O in "oat".
‹ɔ› is like the AU in "laud". If your dialect of English can't tell the difference between this sound and the A in "father", say an /a/ with the lips pursed like the /o/.
‹u› is like the U in "Luke".
‹y› is like the U in the French word "lune". If you are unfamiliar with French, make an /i/ with your lips pursed like a /u/.
Diphthongs (Two vowels smushed together)
‹aj› is like the I in "time".
‹aɛ› is similar to /aj/ but you end on a /ɛ/ instead of an /i/. You can find examples of this in Japanese, like in the verb "kaeru".
‹au› is like the OU in "out".
‹aw› is like OW in "cow". It's found only at the ends of words, or when before another vowel. The /w/ will behave like a transition between syllables.
‹ej› is like the AY in "ray".
‹iu› is like the U in "music".
‹ɛu› is like /iu/ above, except with an /ɛ/ instead of a /i/.
‹ɔj› is like the OY in "boy".
‹ɔɛ› is similar to /ɔi/ but you end on an /ɛ/ instead of an /i/.
‹uj› is like the WEE in "sweet", just with more emphasis on the W than the EE.
Consonants
Doubled consonants are consonants said for a longer duration of time.
‹j› is like the Y in "yellow".
‹l̡› is an L, with your tongue touching the soft, squishy roof of your mouth instead of the hard ridge behind your teeth.
‹ɬ› is said like the Welsh double L, or a drunk slurring S's and L's together. It sounds kinda like the SH sound.
‹r› is always rolled or trilled.
‹r̊› is a voiceless or whispered rolled R.
‹x› is like the CH in "loch" or "Bach". To we native English speakers, it sounds like an over-emphasized H.
‹θ› is like the TH in "nothing".
‹ð› is like the TH in "rather".
‹ʍ› is like the W in "white". This sound is quickly dying out in English, so you may think of it also as a voiceless /w/.
‹ŋ› is like the NG in "sing".
Elvish is from different sources (see credits below), but it is compiled and arranged by Arwen, and also Dreamingfifi of Merin Essi ar Quenteli. Dictionaries and pronunciations are completely by Arwen, but added onto by Dreamingfifi of Merin Essi ar Quenteli. If you wish to use any Elvish sections on your web site, you may, but please state clearly that Elvish is compiled by http://www.arwen-undomiel.com. Depending on what you choose to use, please also credit the sites mentioned in the intro to each section. By no means use all of the info; even two pages is stretching it.