One thing I've really noticed since my dh became a pastor is that people only seem to talk to us if they need something. All the conversations are about them and their problems, their needs, their opinions of what we should be doing, their complains about the church. It would be so nice to have someone care about us for a change instead of us doing all the giving, listening, caring, etc. Even a simple "I'm praying for you" can go a long way. It's hard feeling like all your friendships only go one way, so it's really appreciated when people ask how they can pray for you this week.
Other suggestions:
If you have something negative to say, wait until the service is over. Don't do it right before he gets up to preach. If you have something to say, then say it to his face and don't go to his wife. She is not your go-between and doesn't want to hear what you dislike about her dh.
Don't ask him if he needs a raise. This is like your wife asking you if her outfit makes her look fat. Of course he needs a raise! If you think he *might* need one, chances are he's been needing one for the last 5 years and is too hesitant to bring it up.
If you really want to encourage him, SHOW UP for church, for visitation, and show up ON TIME. When the congregation is singing, look up and smile when you sing. If you can't sing, at least make a joyful noise. All the pastor ever sees is the tops of your heads or half-closed eyelids. Show him your face.
Don't talk during the singing, offering, invitations, etc. And for heaven's sake, get a drink and go to the bathroom BEFORE the service starts. Unless you take water pills or have bad kidneys, stay in your seat during the sermon.
Last but not least, get yourself OFF the back pew and move forward. Not to the front row, as that's sure to give him a heart attack. Just move halfway up like your actually interested in church and not trying to compete to be the first one shooting out the door as soon as he says, "amen."