Christians should make testifying about Jesus good works in their lives a common practice. Luke 8 verse 38 and 39, tells a story of a man that had been set free from evil spirits. Jesus instructed the man to go back home and tell the news about what Jesus had done for him.
This portion is one of many where Jesus encourages people to testify. It is always a blessing and nice feeling to be relieved off of a burden at no cost but only from praying in the name of Jesus. Whatever the blessing God gives, it must be shared with the people so that many may come and share in the goodness of Jesus.
How to testify
You need no complicated verses and theological gimmicks but telling the one thing that Jesus has done for you. It need not be a unique and big miracle but anything that has made a difference in your life from believing in Jesus Christ. This could even be telling the grace of receiving salvation just by confessing with your mouth that Jesus is Lord. It could be the peace we enjoy by being Christians. No testimony is insignificant.
It is important to be brief and specific. The best approach is telling where you were or how you used to be and how Jesus Christ has changed that situation. This is to say you tell of what Jesus has done for you and not what you have done to change your situation. The intension is to magnify Jesus Christ and not you because such may be interpreted as pride to the listener.
Note that there is no age restriction to testify. God keeps doing His work in our lives every time of our lives; young or old. Thus testimony opportunities should be golden to share progress with the Lord Jesus Christ in your life.
Methods of testifying
Methods are plentiful but the traditional is door-to-door, in church, in public places, on television and over the radio. The disadvantage with these methods is that the testimony is normally not stored but delivered once. However, in our time, the information age, it is even easy to spread the word of testimony. I use the internet and others use television and a number of other methods. I have found social networks such as Facebook and Twitter to be other informal but effective methods of testifying.
The message is to the believer that has received the grace of God. Lets share the mercies of God with others so that they also enjoy the beauty of God. TESTIFY!