First, you need to decide what size church you would feel the most comfortable attending--small, medium, large or mega large. Then you have to decide what extra things are important to you--Do you want a strong children's ministry or a strong youth ministry, etc.
Look around at the churches in your neighborhood. Pick about 4-5 churches that are in close promixity to your home. Some of them may have a website to research. Call the church secretary on a weekday morning and find out the times for Sunday school and worship services. If they do not have a church secretary they will often have an answering machine or voice mail that will give you the times for Sunday school and workship services.
Go visit a different church every week for 4-5 weeks. Sit down as a family and have a family discussion about which 2-3 churches you felt the most comfortable attending.
Spend about a month going to each of the 2-3 churches you liked the best. Get involved, attend pot luck dinners, vacation bible school, etc. Make an appointment to talk to the pastor or priest. Really try out a couple of the churches. At the end of the 2 or 3 months have another family discussion. You will know which church you feel the most "at home" attending and you will have your answer.
One last piece of advice. Listen closely to your children on this one. Sometimes kids pick up on things that adults don't even notice. Happy hunting for your new church family!