If you truly appreciate your pastor, attend worship faithfully, regularly, and weekly. Let it be clear that church is your priority and not the place you go when you have no better options or life has hit you hard or you just feel like it. We would have a full church at both Sunday services and on Thursdays if 75% or even 90% much less 100% of the folks who claim to be members actually showed up. What a wonderful problem for a pastor to face! If you appreciate your pastor, go to church every Sunday that you are not at death's door because of illness or at work or out of town (even then, go to church where you are and bring him a bulletin -- pastors love this).
If you truly appreciate your pastor, read the Scriptures, read the catechism, read the Bible and catechism to your children, pray, pray for your pastor by name. Build up your home in Christ. This will not prevent something bad from happening but it will give you cover and a strong foundation on which to stand when the storms come and they will. You carry an umbrella and it does not change the weather but it covers you when the weather happens. Cover yourselves with God's Word, with the doctrine of the catechism, and pray. If you won't do it for yourself, do it for your pastor.
If you truly appreciate your pastor, do not talk ill of him to others. If he has screwed up or offended you, call him up and make an appointment and work it out with him. Would you want your spouse or children to be talking about you to others without talking to you about a problem at home? Why is it okay when it comes to the church? Keep the conversations where they need to be -- directly with the folks involved. This also has to do with any problems you have with others in the congregation. Instead of talking about the people we are in conflict with, talk to them. And when it is resolved, let it be over. That is what forgiveness does. It not only repairs the relationship but leaves behind the conflict.
If you truly appreciate your pastor, take responsibility for something at church that you can do. It does not matter how big or small the job seems but there are countless needs in every congregation that end up on the pastor's plate because no one else will do them. And when you agree to do them, do them. Be reliable and regular and faithful in what you have said you will do. If you are on a schedule, observe that schedule and make your plans around it. If you are an elected or appointed officeholder at the church, then make sure you do more than attend a meeting but do the background work so that you are fully prepared to advise and discuss those responsibilities which the congregation has entrusted to you.
If you truly appreciate your pastor, pay him a faithful wage. Pastors have household expenses, car expenses, and living expenses just like everyone and oftentimes the congregation looks more at what they think they can afford more than what they should be compensating their pastor. Lets face it. The sad truth is that most Lutheran congregations are struggling not because of a lack of funds but a skewed understanding of the money, property, and things they call their own and the duty and responsibility of stewards to put God first in these arenas and not just in the heart. If God is first, there will be enough money to do a credible job of supporting your pastor and his family. Pastors should not have to subsidize congregations who won't support them. When a congregation legitimately cannot, that is a very different issue. A parish of 40 people tithing should have the funds to finance the needs of the congregation and support their pastor faithfully and a parish of 100 people giving the proverbial 2% will have their problems making ends meet and their pastor will suffer the consequence.
If you truly appreciate your pastor, work your schedule around the church. Put catechism before sports and leisure --especially for your children. Model the priorities of the Christian in the home and work and in life. The church is not the last or the least of the things that lay claim to your time but the first priority. Oftentimes pastors end up strung out with weeks and weekends of meetings, appointments, and such simply because their people look at things in terms of what they want. No parish is so big and no responsibility so great that the pastor should be out 4-5 evenings and weekends a week. Have meetings on one night, schedule them to be productive and short, and make sure everyone has done their homework prior to the meeting. It will aid the mission of the congregation to organize.
Pastor appreciation is not about cards or notes (though they are nice!) or even about gifts (though they are also nice). It is about being the most faithful soul you can be in the pew, with respect to your home and family as well as the congregation. Best of all, everyone benefits. You benefit by faithful worship and Bible and catechism study, by prayer and service, and by faithful stewardship and participation in the life of the congregation. So does the congregation. And, in the end, it is the help every pastor is longing to enjoy!