If your black and white prints are lifeless and gray, they're suffering from lack of contrast. This fault could be in either the negative or the print.
To check the negative, hold it about six inches from a lighted piece of white paper and look through it. An ideal negative should have a full range of tones from black to clear, with detail in all areas. The highlights -- which are the black parts on the negative -- should not be so dense that you can't read fine print through it, such as on a magazine page; and the shadow areas -- the clear parts on the negative -- should have detail and not be absolutely transparent.
Assuming the negative, is properly exposed, the fault is in development, not exposure. Poor development can be caused by old developer, lack of proper agitation during development, or underdevelopment. If you send your film to a lab you can't really tell which one of these is the culprit. So, if the fault is in how the negative was developed, try another lab.
If you do your own developing, tighten up your technique for better results.
Pay close attention to time and temperature, agitate as recommended and mark the date of your chemical mixtures so you can use them before expiration.
If the negative is good then the fault is in the printing. Often, it's simply that the wrong contrast of paper was used. Black and white photographic papers come in many grades of contrast, the most popular being a number 2 or normal contrast grade. If the lab doesn't care, or it's out of the other contrasts, they'll use this grade regardless of how flat or contrasty the negative is. When prints are flat, that indicates the need for a more contrasty paper -- such as a number 3 or 4 rather than normal number 2.
Here are some other suggestions. If you're using an outside lab and the negatives have full detail in the highlights and shadow but are gray and without contrast, then either complain to the lab about their development or change labs.
If the negatives look right but the prints look gray and tired, send them back for a reprint on a more contrasty paper.
When doing your own darkroom work:
Keep your solutions fresh.
Pay careful attention to time and temperature in development.
Change the contrast of your printing paper to suit the negative. This can be done by making a test strip on different grades to find the right contrast.