I would encourage you to invest in a good journal and begin now keeping a journal of your devotion time with the Lord. Find a devotion guide and begin making it a priority to read God's Word and listen for His voice. In your journal jot down any key verse or scripture passage that God impresses on your heart.
Journaling is an excellent way to both record and process what God has spoken to us. It's also a useful tool to use at a later time, to reflect on and review some of the "gems" that you have received. Without writing them down, you may forget those blessings and some very important lessons! And while journaling is a very personal time with the Lord, you may want to share some of your daily journaling with your prayer partners or mission team members. Through discussion, you may be able to look deeper into what God is speaking to you, gain new insight and even encourage others.
One popular devotional guide outline is SOAP:
S for Scripture
Open your Bible to the particular devotion guide you are using. Take time reading and allow God to speak to you. When you are done, look for a verse that particularly spoke to you that day, and write it in your journal.
O for Observation
What do you think God is saying to you in this Scripture? Ask the Holy Spirit to teach you and reveal Jesus to you. Paraphrase and write this scripture down, in your own words, in your journal.
A for Application
Personalize what you have read by asking yourself how it applies to your life right now. Perhaps it is instruction, encouragement, revelation of a new promise, or corrections for a particular area of your life. Write how this scripture can apply to you today.
P for Prayer
This can be as simple as asking God to help you use this Scripture, or it may be a greater insight on what He may be revealing to you. Remember, prayer is a two way conversation, so be sure to listen to what God has to say!
You will find that few things provide you more strength and joy than a daily time alone with God. Remember the success of your mission trip is directly related to how much you devote yourself to prayer.