Visualization is like anything else the more you practise it the better you get. However, there is one thing that can stand in your way and that is the difference between what is real and what is imagined.
Take the example of visualizing an abundance of money. You may imagine yourself walking into the bank with a large bundle of cash, taking it to the teller station, placing it on the counter and watching the as the credit to your account is entered. You walk out with a receipt slip showing the large deposit amount.
The imagined scenario may not be the best way to visualize an abundance of money.
As an alternative try withdrawing some cash from your account at the machine or some cash you may have just received. Drive into town and walk to the bank preferably on a nice sunny day when you have no distractions such as a nagging worry which will consume your mind and throw the exercise off-key. Hear the sounds of the traffic and feel the ambience. Look at the bills and take in the intricate pattern and picture. Feel the crisp paper as it slides through your fingers. Savour the experience.
When you walk into the bank take in the atmosphere and feel the excitement as the teller counts the money enters the amount into your account and hands you the receipt.
Each time you do this real exercise, whatever the amount, you will be reinforcing your thoughts of money flowing into your account.