Now, on the other side, being a pastor for nearly 8 years, I've seen some guys make some ministry "No-Noes."
1). Do not invite yourself to preach, teach, sing, lead a conference or hold a revival. It is wrong to call a church or music minister and ask them to host a concert of you for a love offering. If you're doing this, people will avoid you. You have to trust that God will open doors, you don't have to pry them open.
If you're looking for opportunities, you need to "put yourself out there" by connecting with ministry leaders through Facebook, Twitter, blogs, ministry conferences, and conventions. Your resume should be immaculate with multiple pictures and video available to hear you preach/teach/sing. If you get to know people, doors will begin opening.
Also, be aware of everything you're putting on the internet. I know a music evangelist who bashes President Obama on Facebook. Negative comments do not make you more attractive and inviting. In fact, I would not invite this man simply because he comes across online as angry and hateful. Who wants to hear a man sing about how much he loves Jesus on Sunday and then read about him hating Obama on Monday?
2). Be respectful of people's time. Many times the guest preacher says he's going to speak for 30 minutes and it turns into 50. The quartet is going to sing 4 songs and it carries on to 7. The testimony turns into a sermon. If you're not respectful of people's time, they won't ask you to come back.
You always want to leave with people longing for more, not less. Remember, there are nursery and children's church workers looking at their watches while you go on and on and on...
3). Do not have a know-it-all attitude. Years ago I went out to dinner with an evangelist and he told me 14 things First Baptist Moreland needed to do while we were eating. We needed a new microphone, less music, remove the table in front of the pulpit, louder offertory prayer, service needed to start on time, should have bought a newspaper ad, begin offering an evangelism class...
Remember, if they wanted a consultant, they would've hired one. Making suggestions and a "to do list" are completely different. You want to bring encouragement - not an arrogant attitude.