The best source is the Bible. It was written at God's direction to give us help in learning about God. Sometimes I read a little part of the Bible and it really helps me think in wiser ways about how I want to live and about decisions I face. But the Bible is not a magic toy to give us an easy answer. Instead it is a book to be read often and in different ways. It is good to read all the Bible from beginning to end over a year, a portion each day. It is good to read a single book of the Bible, especially in the New Testament, just a verse or two a day to really think about what God might be saying. It is good to learn how to use study guides like a Concordance so you can look up every where in the Bible a particular word is used, like love or obey. I love the internet where I can read a verse or passage in many translations and interpretations to better consider it in context. It is good to participate in an honest Bible study group so you can discuss things the Bible says with other people serious to learn more about God. (By honest I mean this: look for a Bible study group seeking Gods wisdom rather than one who is bending various versus in the Bible to back up their own thinking. Ask for help from the Holy Spirit when you have concerns about this.)
But before there were Bibles, God still revealed Himself to us. And for people who don't have a Bible or can't read or can only understand simple things, God is no less in love with them and no less able to reveal Himself to them. So, when you are watching an awesome sunrise or sunset or listening to a baby's laugh or touching the face of your dying love one, God loves you and will use such moments to help you know God better.
We learn about God from mature Christians who may be our pastor, teacher or fellow worker. I have learned much about God by watching mature Christians love unconditionally. In Bible class I may learn as much from a new Christian asking honest and basis questions as I do from the most educated Bible scholar. Since I can trust the Holy Spirit to help me discern the truth when I ask persistently and humbly, I can speak with a lot of folks about God and use that conversation to seek the truth for myself in Scripture and in prayer, in fellowship and in service and in worship.
In all my life I cannot comprehend or understand or fully know God, because God is God. So it is very exciting to grow in understanding and love and hope, knowing the journey will never end, never become boring, never become unimportant.
* Ephesians 6:10-18