[Pitchwife]

As the part on pronunciation was left out in the German translation of LotR, I had to work everything out on my own in my first (and second, and third) reading. As Estelyn has said, the i's and au's never were a problem, as they have the same values in the elvish languages as in German, so Isengard was always 'Eezengard' to me, and Sauron 'Sowron'. I don't remember precisely whether I said 'Tseleborn' and 'Tsirdan', but I probably did (according to the latin pronunciation I was taught in school); what I do remember is that I pronounced the th's not as in English, but as aspirated t's (=normal t with a puff of air) - until the short appendix in the Silmarillion (which I read about 2 years later) cleared these matters up.
Stress is interesting, too. I first stressed Minas Tirith on the first and last syllables, Mithrandir on the first, but Aragorn on the last. Even today, I say PEL-lenor and PAL-lantír, when I don't think about it.
Oh yes, and Sméagol was more or less SMAY-a-goll to me, so I found it very nassty to hear him called 'Smeegle' in the Bakshi movie. If I understand Tolkien right, the correct thing is somewhere inbetween. Funny - I should have got it right from the start, as the Anglo-Saxon 'éa' and 'éo' both occur in my native dialect (North-east Bavarian)!
Last not least, I too first pronounced the Prof himself TOLL-kee-en, until I read in the Carpenter biography that his name was derived from German 'tollkühn' - so TOLL-keen, 2 syllables not 3, was the only logical thing.

Today, Celeborn has been Keleborn and Minas Tirith Mee-nas Tee-riþ for so long that I tend to find mispronunciations (my own and by others) a bit annoying, seeing that the Prof did his best to explain how it should be; and I certainly get more 'phonæsthetic pleasure' from the correct versions.
Now, would a re-read, consciously reverting to my initial mispronunciations, bring me a flashback of first-reading magic? I doubt it, but it may be worth a try. Ask me again in a couple of months!