Nikon D5100 is an excellent camera and in the right hands can produce pictures that will leave you breathless.
The potential to make good pics is definitly there and with the right lens I see no reason why you cant get very good results with it.
On the other hand it really comes down to the photographer, equipment is one thing but the real problem is with the operator, how good he/she really is.
Learning how to get a really good and professional picture is not about the equipment but is more a matter of tallent and experience.
Give a pro a modern cell phone and give me the best camera in the world with the best equipment in the world and still a good pro will make my pictures look dull and boring.
So yes your camera with few nice lenses will be able to make very, very good pictures but at the end of the day it really is about you, your talent and experience to know really how to use well the camera and get that shot.
Good luck
Ever heard the old adage "You can't make a silk purse from a sow's ear"?
It takes both; a talented photographer with good equipment. Put a cell phone camera in the hands of a true professional photographer (as opposed to a 90-Day-Wonder) and the best equipment made in the hands of most of us around here and you will get a better COMPOSED image from the cell phone and a better EXPOSED and FOCUSED image from the rest of us. A bad camera with a bad lens is always a bad camera with a bad lens, and no matter what you do or who you put behind it you will still get poorly exposed and focused images.
The D5100 is a decent camera but it isn't a professional camera. It is certainly capable of exceptional photographs in the right hands, but they MUST be experienced and knowledgeable hands. The OP has indicated that they are "New to photography" and are already concerned about trying to "get my clientele up". My suggestion would be to stop worrying about equipment and worry about the photographer for a while. If you are truly new to photography then you have not even come close to reaching the limits of whatever body or lens is presently in use. Use what you have and when you reach the limits of a lens or body you will know, and you will know what direction you need to go.