Good question.
I find "reverend" to be pretentious, so ignore it and won't use it in regard to anyone else.
The term "pastor" means shepherd, and is, in my opinion, the greatest compliment I can be paid. A shepherd cares for the sheep. He is the tool of the Master-shepherd. His life is focused on ministering God's Word to His people. In light of this, he either is a true shepherd, or he is not. If he is, call him "pastor" out of love for him. If he is not then don't denigrate the true shepherd by calling a hireling "pastor." Let him be reverend - he can have it.
In light of this understanding, I do not call myself pastor. I answer to it. If someone asks if I'm the pastor then I say I am. But I do not present myself, nor sign my name, "Pastor Joe." As far as I'm concerned self-given titles are self-promoting titles, as are letters after one's name. Give honor where honor is due, sure, but that doesn't mean we seek it for ourselves... we might find ourselves relegated to the back seats in the synagogues. Men who seek the respect of men will get their reward. True shepherds have a greater reward as "good and faithful slaves."
Once in a while someone comes along calling me "father." But they always want something, usually money.
What it comes down to: If you write me a letter, call me by my given name. If you introduce me, introduce me by my given name. If I shepherd you, or you can with confidence call me a true shepherd, then feel free to call me "pastor." It's humbling, thrilling and convicting while conveying honor and respect; as long as one remembers the nature of the calling.
Blessings
Just plain old "Joe," a slave of Christ