Yes, the easiest way is to keep a journal of every feeling and every insight (voices/thoughts) that come to you. Write in it every day, even if you don't think there's anything to record. After two weeks or so, go back to older entries and see if those things you wrote about actually happened. By doing this, you increase your observational abilities and will begin to notice patterns, especially if you always note the times and situations when your intuitive voice comes through.
In that way, you'll be able to know when you are simply thinking random thoughts or when a real message is bubbling up from your subconscious.