First -- if you are looking for God, do you really know what you are looking for?
Are you looking for a man? A woman?
Are you looking for love? For continuity? For a profound experience?
Are you looking for a sense of peace and stability in your life?
When you say "God," what do you really mean?
We talk about God all the time at Church and with other believers, but how often do we stop and really think about our perception of God? Is God a King to you? Is He a separate entity hovering somewhere in space or another dimension? Is He something abstract, a word, or a sense of meaning that you are lacking from your life? If you are looking for God, where are you looking, and what are you focusing on?
These are extremely important questions to consider if you are looking for God. Change what you are looking for, and you might just see it.
Here is a simple way to know God:
Pray.
And watch.
And keep your eyes open.
Remember: God is not something that you control. You cannot "force God to show Himself," as though you were herding a deer into an open meadow. God has His own timing and way of doing things. Do not look for an angel in the clouds or an unexplained envelope of money in your mailbox. God is right in front of you, but this is not how to see Him.
Instead, be patient. Pray, and watch for opportunity. Look for coincidence in the world around you. It is difficult for the mind to understand, but God is the world, God is your heart, and when you begin praying/communicating with God, you begin moving by His timing, then His blessings and bounty begin to fill your life by otherwise ordinary means. No, you will not receive an unexplained envelope of cash in your mailbox... but suddenly you might receive a raise at work. Stop looking for God in the clouds. We are already living inside of the miracle. Watch how it works around you.
Seeing God has nothing to do with where you look. It is the eyes you see with. God is all around you, all the time, but we do not see Him because we are not "wearing the right glasses." To see God, we must change our internal perspective. We must believe in Him and trust that, if we ask, He will make Himself known to us. And then, when coincidences begin to happen, we must not close our eyes. It can be terrifying at first, seeing God work in our lives. It is strange and exhilarating, suddenly feeling as though the world is moving to accommodate for us. But do not turn away. Eventually God will be more than coincidence, and you will know His Presence in everything, and then you will see God and Life for what it really is.