Hey so if you're reading this and you've never really read the Bible at all, here is what I recommend...
I highly recommend you approach this little "dig" with a clear foundation of books of the Bible we've been given in our modern canon.
Sure, if you get to Genesis 6 and can't understand why God would flood the whole earth and if that makes you want to put it all down, then go read 1 Enoch and then jump back into Genesis. That really trips people up and Enoch is where we get the details instead of the summary we get in Genesis. (Remember Genesis was written to Hebrews who already understood the details!)
The foundation for all these books is the story of God saving humanity from our sin and how Jesus died, went to Sheol and took the keys so that He may be the ruler of a New Kingdom to come and how He is our High Priest atoning for all our sins on our behalf. And that all we need to do to become part of that eternal Kingdom is simply believe in Him. It's the story of Gods GRACE, through faith in Jesus and how He will restore the Earth back to how it started. This is the story of the modern canon.
If these new books do not fit into the story then they are false, so you can't know whats been added to deceive us and what's actually true without knowing the foundational characters and story. Most of these "extra books" add more details to the modern canon in the times when God just needed to paint the overview.
Also you really need to pray and fast while you read these.
Let the Sprit the Lord has given you be your guide. It's not all knowledge. The Good Lord may not want you to go down this path right now and His reasons are always GOOD so pray over it first and keep praying over it as you read. This is an investigation, not necessarily your quiet time. I hope that makes sense.
....but for those of you ready to dig dig dig, well let's go!