I don't wear a cross, but I don't wear much jewelry, either.
But there's a specific reason I usually don't wear one.
God calls me to people who have been abused, usually in childhood, by people claiming to be Christians, and/or their abusers were enabled by people claiming to be Christians.
I once read a story about a middle-aged man who was repeatedly abused as a boy by a priest. He said that he always saw the priest's silver cross shimmering in the light while this priest was abusing him.
For him, the cross symbolized people claiming to have a direct line with God, then using it to abuse others in terrible ways.
I tend to have a very neutral (harmless) appearance to others (or I try,) and after some time (at work, in volunteer groups, etc.,) people often open up to me about their deepest hurts. Imagine what it's like for the many people who have been sexually abused from the time they were toddlers by someone claiming to be a Christian, while others (their other parent, for example,) who also claimed to be a Christian, looked the other way. One woman I talked to was abused by a pastor and a policemen, with a coach also later attempting.
Some were even told, "This is how God wants you to express love," or "God made you for this."
Can you imagine?!!
I'd be pretty apprehensive about anything having to do with God or Christianity, too.
So, I just try to hang back and get to know people, let them vent their hurts, get a feel for where they are in their journey.
I then usually ask, "Have you ever tried... talking to God about how you feel?" and kind of go from there.
I have no qualms about sharing my faith -- I used to have an "In God We Trust" license plate, and, when I got to know some fellow employees, carried a Bible to read on my breaks. This began an interesting conversation with an atheist and a Jehovah's Witness.
I just choose to be selective about when to share and how much as I learn what others share and see how they respond.
I like to say it's my "Ester calling."
Like Esther, I started out life as an orphan, was adopted, and have found my witness most effective when I share my faith strategically.