Be humble. Learn all you can. There are great resources in books, videos, online websites, missions agencies. But drink most deeply of Bible and theology from solid sources. Read Acts over and over. See the progress of the Gospel through the New Testament and through the centuries.
Read good biographies of missionaries.
Pray for the world with resources that inform you about the unreached, their access to the Gospel or lack thereof, the percentage of evangelical Christians, the barriers to Gospel proclamation.
Get to know good solid missionaries personally. Get on their newsletter list. Pray for them.
Get some experience in other language/s and cultures around you.
Volunteer for service or teaching English to immigrants.
Invite foreign-born coworkers or university students to your house for a meal, for a sports watch party, for a holiday. Explain what you know and believe about the Gospel to them.
Spark your church family by sponsoring/hosting a missions prayer group, a support group for a particular missionary, an outreach to immigrants or foreign students in the range of your community.
Read more books aimed at equipping you to ministry to Muslims, Buddhists, Hindus, atheists, or agnostics.
Learn something about apologetics, defense of your faith, and common contemporary arguments against Christianity.
Read a one-volume biblical Systematic Theology.
Head - knowledge and content
Heart - passion and conviction
Hands - experience, doing, competence