I guess the best way to answer this question is to give an illustration: years ago, I started bowling. I fell head over heals in love with the game. I was not at all proficient, I made many mistakes. So I took it upon myself to practice faithfully. In time, I was able to acquire a skill, and attain a certain degree of success. After practicing and doing the same things over and over, when I did make a mistake I could recognize my error immediately and correct my fault. You can apply this to the scriptural principle, to practice ones biblical conviction and in time, you will recognize a sin or that you've gone off the path immediately. Repent, and get back on.
To grow in maturity is to work hard, study, to see what God is really telling us, and not to rely on preachers or teachers to explain the Gospel to us, but to have them, give us confirmation of what God has already told us.