Avoid the churches that claim to be the only church.
Avoid the chuches that tell you you're going to hell if you don't go to their church.
Non denominational is fine but avoid those in which one person is the absolute authority even if he seems to be straight arrow and saintly. Choose one in which the pastor or pastors work with a board of elders or other group of lay people to establish policy and solve problems.
Choose a church that has an active, thriving youth group with religious instruction and other activities. Usually a really good praise band or a youth choir is your first clue that you'll find the kids involved and loving being part of the church instead of out raising hell someplace.
Choose a church that encourages members to also meet together in small groups separate from the main worship service. That will be a church that is likely to take its role seriously and is doing church the Biblical way.
Choose a church that greets people and you see a lot of smiles and hear a lot of laughter. If all you see are gloomy faces or frowns, run, don't walk to the nearest exit.
And when you're visiting, if it feels uncomfortable or just doesn't feel quite right, trust your gut and visit somewhere else.