Step 1: Make sure they use the King James Bible, God's word for the English speaking people if you speak English.
Step 2: Make sure they have salvation my faith in Jesus Christ's death, burial and Resurrection from the dead for the payment (remission) of sins. Many churches have salvation but they add you must live a good life, join their church, do good works, do another religious act (example.. baptism, communion,pray in tongues) these things are not necessary for or to salvation good works come as a result of trusting Christ. After you receive Christ you naturally want to please him. This is the right order not the other way around.
Step 3: Make sure they soul-win. If they don't believe in actively giving out the gospel then you have a dead church. A church that isn't going out isn't sharing what God can do for others. They are keeping it a secret. A city that is
Step 4: Are they scriptural? May times you can tell right away if they are scriptural if you ask about their salvation and ask them what they teach about the way one gets to heaven. Also ask them if there is something you have to do keep that salvation.
Step 5: Pray for God to lead you to the right church and to give you wisdom to make the right decision. Not a decision based on how sweet people are or how pretty the church is or what neat programs they may have but in the right teaching of the church.
I go to a Fundamental Baptist Church because the teaching of that church comes straight from the Bible and not from extra books or traditions.