Seek the truth. Look for it. But don’t just look, search! Go dig for it! Go move things around to find it! Be aware and ready, because sometimes it will be suddenly found. Be aware and ready, because sometimes it is slowly revealed. And do be careful! Sometimes you will find something that calls itself truth, so it is good to know what you’re really seeking. You’ll likely have to do a lot of cross-referencing, and maybe more seeking, but you can know the truth as well as seek for it.
But seeking isn’t enough. When you find the truth you should study it, thereby knowing it even better! And the better you know the truth, the easier it will be to seek more. The better you know the truth, the easier it will be to spot a lie. The better you know the truth, the more truth you will seek.
But where does one start? With God and with His words (Psalm 25:4-5 and 33:4). Go read the Bible. Go get to know Jesus and who He is (John 14:6). Believe in Jesus and do what He says (John 8:31-32). Listen to the Holy Spirit (John 15:26).
I’ve written other things on truth if you would like more: “What Is Truth?” and “Hidden Truth“.