What is the greatest tool for evangelism you and I have? Read the words of J.C. Ryle from his book Holiness:
"We must be holy, because this is the most likely way to do good to others. We cannot live to ourselves only in this world. Our lives will always be doing either good or harm to those who see them. They are a silent sermon which all can read. It is sad indeed when they are a sermon for the devil's cause, and not for God's. I believe that far more is done for Christ's Kingdom by the holy living of believers than we are at all aware of. There is a reality about such living which makes men feel, and obliges them to think. It carries a weight and influence with it which nothing else can give. It makes religion beautiful, and draws men to consider it, like a lighthouse seen afar off. The day of judgment will prove that many besides husbands have been won 'without the word' by a holy life (1 Pet. 3:1). You may talk to persons about the doctrines of the gospels, and few will listen, and still fewer understand. But your life is an argument that none can escape. There is a meaning about holiness which not even the most unlearned can help taking in. They may not understand justification, but they can understand charity. I believe there is far more harm done by unholy and inconsistent Christians than we are aware of."
In short, the greatest tool for evangelism you have is your personal holiness.
I am a Husband to Clarissa, Pastor at Liberty Baptist Church, reader of many books, and tweeter at @brad_merchant.