The outfit you wear to church really depends on the church. In many more traditional Catholic churches, women are expected to wear some kind of head covering—either a hat or scarf. In most more traditional churches of all sects, women usually wear skirts or dresses and pantyhose, with conservative shoes like low heeled pumps. Men usually wear either suits or a coat and tie over dress pants and shoes.
In some churches, people dress up more for the fun of wearing their "Sunday best" rather than fear of annoying their church elders. Because attending church is largely a social event, people put on their favorite hats, skirts and jewelry just to look nice and mark the day as something special and set apart from the workaday world. In most churches as in much of society, it's considered incorrect to wear perfume: so many people have allergies and asthma these days, that a little bit of scent, however nice it smells, can be a dangerous thing.
But lots of churches have embraced a more casual style, and you'll see members of the congregation dressed in jeans, T-shirts and more playful clothes. If you haven't attended a particular church before, it pays to do a little homework. If you don't know anyone in the congregation, call the church office and ask what people usually wear to services. If you're feeling too shy to do that, err on the conservative side as you would for a job interview: you can always lighten up next time.
