If your soup is too bland, you are simply not using enough salt. Period. If you had said that the soup lacked the rich flavor you had tasted in other people's soups, then that would be different.
Here's what I've picked up when making soups, for what it's worth.
Simmer, simmer, simmer the chicken (or whatever else you're using) and vegetables to make a rich, flavorful stock. When you are done simmering them, simmer them some more. I have done this to the point where I have reduced the amount of liquid by 1/3 the total volume.
Then, let it cool and refrigerate it overnight, with the chicken and vegetables still in the pot.
The following day, strain the liquid and make your soup. This will get you a very flavorful soup but, if you don't add the proper amount of salt, it will always be bland.