Religion and The Bible

Preachers use "The Bible" as their guide and tell others that it is the word of the Lord.
While no book is written by the Lord.
It was mostly written by apostles, prophets and other servants of God.
While it tells us God's acts and some of God's "quoted" words preachers use this to give messages.
messages that sometimes include personal experiences. Sometimes too personal.
In the book of Revelations, it tells us that there will be plenty of false prophets after the Lord's ascension.
That begs the question. How can we tell? How can we differentiate the REAL preachers from the FALSE?
because listening to other preachers sometimes makes me realize that the message that they are telling does not get close to what The Bible is telling us. Sometimes it's just a message that they want to tell the people.
So, should we believe them? or not?