In the third book of John, we see the Apostle strongly encouraging his friend to participate in the sending out of missionaries. He not only strongly encourages this participation in missions, but he exhorts his friend to do it "in a manner worthy of God."
III John 1:5-8 Beloved, you do faithfully whatever you do for the brethren and for strangers, who have borne witness of your love before the church. If you send them forward on their journey in a manner worthy of God, you will do well, because they went forth for His name's sake, taking nothing from the gentiles. We therfore ought to receive such, that we may become fellow workers for the truth.
John tells his friend to do whatever he does for the ones being sent in a faithful way; meaning to do it in a way that can be trusted and relied upon. Let them know you are with them and have their back, so to speak. It is good advice, because it helps those in the mission field to know that they can vigorously go about the business of the gospel without surrendering too much energy to the meeting of normal daily needs.
John goes on to say "if you send them forward on their journey in a manner worthy of God, you do well..." To send them forward with great prayer and encouragement is to send in a manner worthy of God. To send them forward with "above and beyond" financial support is to send in a manner worthy of God. To send them forward with a promise of sustained and future involvement is to send in a manner worthy of God. That those being sent took nothing from the gentiles is significant as well - meaning that the senders and the sent ones bore all the burdens.
Finally, John concludes that by sending in a manner worthy of God, the senders can become fellow workers for the truth. And fellow workers receive like rewards. So pray for your missionaries, encourage them with great encouragement, and send them forward of their journey in a manner worthy of God!