I'm working on translating a poem that I wrote in English, and here are some of the resources I've been using.
Quenya Wordlists -- from Ardalambion. Both English-to-Quenya and Quenya-to-English wordlists can be downloaded.
New Words -- If you can't find an attested form of the word you're looking for, the next best thing to go with is a "reconstructed" form.
And now, a grammar question: for my poem, I want to say "much longer". There are different forms of "much" for whether it is an adjective or an adverb. In my case, what would it be? Adjective, I think.
EDIT: Never mind, I figured it out... and I was wrong. It's an adverb.