Summer vacations are not the only trips in view when the last school bell rings and the neighborhood pool opens. For many of you, these things also mean that your summer mission trip is just around the bend. It's good that you begin thinking about it now. You'd be well served not to wait until the week (or night) before to begin preparing for it.
So here are some simple ways to get ready, between now and the airport terminal.
Begin Praying Now. This should go without saying, but prayer must undergird any sort of ministry in which you engage. Why? Because you can't change people; only God gives new birth. Your dependence on him for this should be evident in your prayer life. If you aren't praying, not only may your missions goals be too low, but your trust may be misplaced.
Know Your Team. This may already be happening, but if you aren't meeting with your team before you leave, try to get together with them soon. While praying together and planing together have enough merit on their own, meeting with your team will also help you discern personalities and roles. One of the greatest opponents to your effectiveness as a team is disunity, and spending some time together before you find yourselves in an unfamiliar and/or stressful context may help to prevent any potential quarreling.
Rehearse the Gospel. I was privileged to spend a summer on mission in East Africa. I had been warned that on-the-spot introductions to speak were common. As it turns out, that couldn't have been more dead on. At one point I was actually handed a megaphone in a crowded market. Thankfully, part of that warning came with an encouragement to prepare a gospel presentation. I would encourage the same. Even if you're not going to a culture where impromptu sermons and megaphone preaching is common, it would be still wise to prepare a clear and concise statement of the gospel that you could share at a moment's notice.
Look to Local Partners. I doubt you are unacquainted with the mission of your local parters, but if you are, get to know their vision before you get there. Little could be more encouraging to a long-term missionary than showing genuine care for the ministry they've devoted their lives to. But more than this, doing your homework will also tell you how to best come alongside them in their work. On a short-term trip, your time is best spent serving the long-term partner since they'll be there long after you leave. So take a back seat, follow their lead, and see what will actually serve them longterm (not just give your team the best experience). And as a side note, you can begin serving them before you go by asking them if there is anything you can bring them from home – like care packages from loved ones, books, and even snacks they cannot get in their local country.
Be Ready to Grow. Don't substitute your personal walk with Lord for serving him on a mission trip. It's incredibly easy to place all your focus on your team, the work you're doing, the travel plans, and all the sights to see. In doing so, you neglect communion with the source of your power. You must proactively combat this tendency to forgo your daily devotions on the trip. So before you leave, come up with a basic plan for reading your Bible and prayer. Also, expect to learn and grow a lot through what you do and experience; it would be prudent to have some sort of journal in which to process your thoughts.
Plan for Change. Though flexibility is key on the mission field, being flexible is different than not having a plan. In fact, flexibility often requires more planning. When your in-country transportation is running two hours late, have a section of Scripture ready to begin (or continue) memorizing. If the ministry plans fall through for a day, have some sort of backup plan in place to encourage your teammates and/or local partners. If a more pressing need arises, don't be so married to your original itinerary that you can't adjust. Humbly serve according to the advice of trusted local leadership even if it diverges from your preconceived notion of service. And if something strange is placed on the dinner plate before you, it's time for you to expand your palette.