There is no single answer to that question and sometimes it's difficult even finding a place to begin answering it. Dan Bacon's book "equipping for missions" has become an invaluable resource in our church's efforts to help individuals take those first steps in addressing their sense of calling to missions.
Chapter by chapter, Dan begins to unpack each of the important issues involved in affirming a call to missions, identifying the strategic needs for completing the task, the importance of prayer and the critical relationship that should exist between the sending church, the agency and the missionary. As much as the book encourages people to "go," Dan also affirms the role of those who stay and "send" and allows the reader to discover his or her unique role in God's global purposes.    
Also available for your Nook & in the iBookstore.
While cyberspace and concorde jets have made the world so small that East and West meet regularly, when it comes to understanding one another, the two worlds are as far apart as ever. This book deals in broad strokes with the major differences in the mindsets of the two groups, not to encourage prejudice, but to evaluate these world views.
Also available for your Nook.
Serving As Senders: How to Care for Your Missionaries While They are Preparing to Go, While They are on the Field and When They Return Home. The title says it all! A missionary needs care in at least six areas: Moral Support, Logistics Support, Financial Support, Prayer Support, Communication Support, and Reentry Support. This book gives scores of practical ideas in how a team can provide the necessary care for a missionary. Chapter One tells "when" and "why" a missionary needs care. Chapters Two through Seven deal with each of the six areas of care. Chapter Eight brings it back to the individual's involvement in care giving.    Also available for your Nook & in the iBookstore.
Also available for your Nook & in the iBookstore.
Dr. Neil Anderson of Freedom in Christ Ministries writes in his foreword:

"There was a time I thought I could explain the world through the grid of my Western rational and natural world view. When I turned to Christ for my own salvation, I was taught how to explain the failure of humanity by the nature of the fallen world and the ongoing struggle with the flesh. I learned about the kingdom of God but was taught little about the kingdom of darkness. Then someone put Arthur Mathew's book 'Born for Battle' in my hands and I began to understand the nature of the spiritual battle that believers are called to engage in. `Born for Battle` is one of those Christian classics that needs to be read again and again by every generation. I trust it will do as much for you as it has done for me."
I know that many of you may find some of the stories contained in this book difficult to believe; Western education teaches us to automatically question demon possession, spiritual warfare, and the supernatural—especially when an occurrence cannot be confirmed by empirical evidence. But Eastern society operates much differently. In fact, missionaries have found that most Taiwanese people, especially those belonging to the lesser-educated working class, unfalteringly believe in an active spirit world. 
That being said, I’ve tried my best to retell these life histories just as their main characters have described them. I’ve refrained from including personal judgments about the causes of their behavior and experiences—especially in those of a more “unusual” nature. I hope that you too will refrain from making personal judgments about the men and women you are about to meet just because you may not wholly agree with their theology. 
I hope that the stories in this book will break your heart—as it has mine—for one of the most overlooked, spiritually hungry nations in the world. 
                                                                                                                                                                               - Jennifer Su McIntyre
Also available for your Nook & in the 
iBookstore.

Leadership

This booklet is a short reflection on the life and leadership of D E Hoste who succeeded Hudson Taylor as leader of China Inland Mission (now OMF International) and led this movement for over 30 years. "The title comes from the fact that Hoste was determined that his name and reputation would be subsumed under the desire to see Jesus get all the honour for everything." (Quotes by Ajith Fernando.)
Also available for your Nook & in the iBookstore.