The call to evangelise is a general responsibility for all believers. However, we are not to work it out in our own strength. The Holy Spirit has come to empower us for evangelism.
Jesus said, 'You shall receive power when the Holy Spirit come upon you.'
We are thus enabled to work the work of the Holy Spirit since He lives in us. If we are sensitive to the Holy Spirit, He can do greater things and His work thru us.
The ministry of evangelism is to tell the good news to the world. In order to do this, we need great boldness. Boldness is not something we can have if we trust in our own strength. Boldness comes when we trust in God and believe that He is able to do anything.
Filled with the Spirit. When the believers in Acts were filled with the Holy Spirit, they did not have their 'Holy laughter' nor were they shaking their hands, they spoke in other tongues. Similarly, when a person receives the Holy Spirit, he or she will speak in other tongues. Speaking in tongues is then a sign to the non-believers, for the others were marveled when the apostles and the rest waiting upon the Holy Spirit spoke their own language. This sign, therefore, brings unity of heart as we now speak of one heavenly language to God and to men (if we know its interpretation or the tongue is the language to the other).
Evangelism is therefore more than just getting people saved and confessing Jesus. It is to have the world know and recognise Jesus is LORD.