good way to practice visualization is to think of something you don't normally see during the course of your day and keep an image of it in your mind until it comes into your realm of experience (which it will.) Don't pick something you normally see, for instance if you live in the country, don't think of a cow or a horse because chances are you'll see those anyway. Instead think of, maybe Michaelangelo's sculpture of David. Keep the image of the sculpture firmly in your mind and keep it there all day. Before long you will see David somewhere. It might be on a sign, or a bumper sticker or maybe a TV show, but David will come into your realm of experience, which will reassure you that through your mind, God creates your reality.
This is a rewarding experience and is something I practice often. A few days ago just for fun I decided to try and manifest a pig. I visualized a pig all day, and the particular pig I kept in mind was the familiar Arkansas Razorback boar with his fierce sharp tusks. All day I kept the image of this pig in my thinking while continuously looking to see a pig somewhere. I didn't see my pig all day long but I remained faithful in the belief that I would. On my way home from an errand I stopped at the grocery store to get something for my dinner. On the wall behind the delicatessen counter there was a big sign advertising Boar's Head Deli Meats. Their logo is (of course) a boar's head, complete with the sharp tusks that I had been visualizing. Even though I had been expecting to see a pig, the fact that it was virtually the exact pig I had been envisioning sort of blew my mind.
Try this for yourself. It's fun, and as it becomes easier and easier to experience the reality that God creates through your mind you'll be able to experience more and more of what you want and less of what you don't.
Always have faith that the thoughts you hold in your mind create your own reality. Without genuine belief it won't happen. Every successful person in history, without exception began his or her journey by believing that they would accomplish what they wanted to. Countless others have wanted to achieve success but did not possess the belief that they would. Of course we don't know them, for they did not reach their goals.
"I tell you, if anyone says to this mountain, ‘Go, throw yourself into the sea,’ and does not doubt in their heart but believes that what they say will happen, it will be done for them." - Mark 11:23
I used to read this verse and think "No way man," but after thinking about it for some time I began to interpret it as meaning that you need to truly believe something will happen in order for it to happen. Which is why none of us will ever make a mountain throw itself into the sea. No matter how hard we think about it we know (at least we believe...) that it ain't gonna happen. And so of course it doesn't.
The key to manifesting your reality is to truly believe in it. And be grateful for it now, not later, for it will not take long to appear.