The greatest advice I can give to people here is this:
Realize from the core of your heart and soul that your mind IS your World. Meditate on this last sentence for few days so that you understand it not just intellectually but profoundly.
When you imagine or feel you often do this to change outside world, and often you worry how and when will it be manifested. You think of your thoughts as somehow “unreal” and you wait for the “real” reality to manifest… and so of course you weaken your power. This is erroneous thinking. This blocks your progress and manifestation. Because it is ignorance.
Pretend that only your mind exists: nothing else, no one else. Nothing and no one to change but your mind. So focus on your mind only. Cultivate thoughts, feelings and mental images that you want without ever being influenced by the outside. Don’t even wait for results: do this just as a game. See those thoughts as a manifestation in them self. If you persist in this way: with the understanding that your mind is the one and only reality and that the moment you changed your thoughts and feelings you changed your world, the outside reality will have no choice but to change.
But please: don’t change your mind so that you change the outside, understand that the second you do this in your mind the reality IS ALREADY changed so the question “when” and “how” vanishes. The time lag is only an illusion. Do this for few weeks just to play with this idea: do it just for fun to see what will happen. Enjoy your desired thoughts and mental images as a manifestation in them self and ignore the evidences of the senses.
Of course if you do this, even for fun you will find the secret of creation. You will feel great power. Your manifestations will be very quick, physically speaking but never, ever make yourself or your mind dependent of it.