The answer to this question depends a lot on what you're starting line is. 

It's a vastly different answer if you're starting line is as a high school student versus as a college graduate versus a married person with a spouse and a career and a bunch of worldly possessions and children.

Let's go ahead and state some obvious assumptions:<

• You're a believer with a clear testimony of salvation and solid ministry involvement in a healthy local church.
• You have already spoken to your church leadership about your interest in missions, in general, or becoming a missionary, and specific.
• You are willing to make changes in your life and/or direction in order to prepare well for ministry on a cross-cultural mission field for the long term.
• If you are single, you have informed your parents of this new direction and, if they are believers, they generally agree that it's OK.
• If you are married, you have discussed this with your believing spouse and he or she has agreed that they are in it with you.

If your church has affirmed your inclination or compulsion to pursue missions ministry, they will need to get up to speed on how to help you prepare.  There are a lot of elements to think through, work through, and decisions to be made.

Regardless of what age or stage you at with respect to life, you will need to do a number of things to prepare well for the field. Here's just the overview list, below. A great primer for the process would be Propempo's book "Here to There: Getting to Your Missions Field"

1. Get adequate Bible and theology training.
2. Get experience in evangelism, discipleship, and training of others.
3. Get an understanding and at least an observation of how church leaders operate.
4. Research, discover relationships and get information about how missionaries operate day-to-day in life on the field.
5. Begin to narrow down the possibilities about where you would go, who you would work with, what mission agency would be your guide and corporate family on the field.
6. Build strong cross-cultural experience and skills BEFORE you leave this country!
7. Get a handle on the process and grueling, humbling, steady commitment of language learning; perhaps take a class on language acquisition or, better, take a course in the target country's primary language.
8. Decide, with our church leadership, on the best mission organization to affiliate with to achieve the church's goals for you on the field.
9. Apply, attend candidate training, and comply with that mission organization's prerequisites for departure.
10. Discover God's provision of support through personal fund-raising and vision-casting for your ministry "over there."

There are a lot of refinements to the list above. Try to answer questions like this:

1. What part of the world are you drawn to? Do you have relationships already with people from there or who live there?
2. Do you already have some language skills that you want to use that would narrow your focus?
3. What are your specific ministry roles or desires or skills or giftedness you think God may use?
4. What kind of team would I like to work with? What end goals would I contribute to?
5. What do wise, godly people around me say about my talents, skills, strengths, and possibilities?

We pray that you will seriously consider and count the cost as you begin down this pathway.

Less than 1% of Christians aspire to become a missionary.

Only 15% of those who say that they feel called to be a missionary actually qualify to go and do it.

Only 25% of those who go to the field actually stay long term enough to make a significant impact in faithful, effective, fruitfulness. 

Will you be one of the 15%?  Will you be one of the 25%? 

Do the math!  If God equips and enables you to have the high privilege of doing it for the long term, you would be one of only 4% of those who start the journey who make it to the finish line. May God make it so!