This goes for any ability from telepathy to future prediction. Without that clarity of mind, your abilities won't develop as they should. One of the most common ways to produce this clarity is through various types of meditation.
Meditation is a centuries old technique that teaches people to clear their mind and focus. Without that constant din in your head, you can work on focusing your thoughts on your own mental abilities. There are many different ways to meditate from classical to transcendental. There are people that will offer to teach your for money, books are available and countless web pages to read.
However you choose, the key to meditation is practice. After a lifetime of being conditioned to have a crowded mind, leaving it all behind and embracing the quiet won't be easy. It takes time and patience to understand the methods of meditation.
Many people try it only to quit when it doesn't come easily to them. We live in a world of car horns, construction and conflicting thoughts. It is a time of chaos and only by adhering to the techniques for the long haul will you be able to finally master your own mind.
The limit of your abilities is only gauged by your dedication to develop it.