Just so you don’t feel too alone, I’m also fairly fluent in Spanish, but I’m not a teacher ;).
The best way I found to learn Spanish though was to buy the 500 Spanish Verbs book (even the 300 one is ok), and study it religiously. Other than the verbs and the tenses most words in Spanish are close enough to English that you can figure them out, and pronunciation is never a problem. Once you know the pronunciation rules they stay the same, so if you can write the word, you can pronounce it.
Another think I did was tag absolutely everything in my house with the spanish word. I mean everything. I had tags on spoons, forks, knives, even the stuff in my junk drawers.
Then read a Spanish newspaper everyday, and look up every word you don’t know. It sounds tough, but it’s not.
I did all the above for an entire year when I met a woman in the Dominican Republic one winter. The next year I went to the DR for two months and came home fluent in Spanish, engaged to her, and the marriage lasted for two children and 10 years :).
Brad.