Hold fast on the true word of God 

Holding fast the faithful word as he hath been taught, that he may be able by sound doctrine both to exhort and to convince the gainsayers: Titus 1:9

The true teachings of the gospel must be received and well understood. If the gospel is taught well and you did not receive the gospel as it were to be received, those that would be taught by you might be led astray by your wrong doctrine. The scripture says you must study to show yourself approved. (2 Timothy 2:15) Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth. A believer of Christ who received the true teachings of Christ will lay a solid foundation and sound doctrine for those who will hear Him/Her preach. 

As an ambassador of Christ you must receive the right and true teachings of the gospel. The Holy Spirit should be your closest partner when studying the scripture to reveal things that seem mysterious else you might be reading the Bible like a novel.

Conclusion:

Hold fast on the true words as you have been taught so that those who will hear you teach or preach will receive a sound doctrine of the gospel.