M.P.
I've looked for churches and would usually start out going to the Sunday morning service at those close to me geographically. It's so convenient to not have to drive a long distance. Protestant churches often have a card to fill out when you're new so that someone can contact you, either by mail or in person, to welcome you to the church. You then have the opportunity to ask about the church, it's beliefs, membership, Sunday School classes, etc.
You also will get a feel for the atmosphere and whether or not it seems agreeable to you. You'll see how the kids dress. You'll meet some of the other people after the service. For me a good indicator of whether or not I wanted to return was whether or not anyone talked with me.
Many churches have a coffee hours after the service. Go to that and get to know people. Ask questions about the church and their beliefs.
Some churches have a special service for kids. They can sit with you or go to another room with that group.
In my daughter's church, the kids wear jeans and khaki's. Even the younger adults dress somewhat casually. I'd say office wear is fine.
Go to several churches and then choose the one that best fits your needs.