What restricts a person's spiritual growth is a lack of attention to God's word. What will help is to read the Word of God, daily, systematically and prayerfully.
Here is a link to a website that will help you in your daily reading of God's word. It has a system of readings and also comments on those readings from Bible students around the world which will help you understand what you are reading: Daily Bible Readings
Here is another link to information that will assist you with this question: Getting to Know God