In 1805 William Carey and some friends signed an agreement about what they wanted to focus on while reaching the unreached.
Here is a really rough and quick summary:
Care about the state of the lost.
Learn what we can about them, by talking to them and studying.
Be culturally sensitive and avoid unnecessary offence.
Work hard at meeting and talking with the lost as much as possible, day in, day out, not just in a couple of events or programs a week.
Tell them about the death and resurrection of Jesus. This is our main message.
Be humble and available to the locals.
Work hard at strengthening and caring for the ones that believe. This takes lots of time and patience.
Encourage the gifts and ministry of the local believers. They are the ones that will carry on the work in their own culture, not us.
Work hard at learning the language, translating the scriptures, and distributing them.
Above all, maintain a vibrant personal prayer life.
Finally: Let's give ourselves fully and waste our lives for this cause. We can never think that our lives, skills, families or possessions are our own. We have to give all that up for Jesus. Let's forget about saving up for ourselves or our children. Let's drop any petty quarrels, and live together for Him!