Most Helpful Girl
Personally, I would hate to see someone change who someone is...but if you are really wanting to, then okay.
I would say depending on how much you are willing to spend on clothes. If you're "a jeans/t-shirt guy wanting to spruce up the image" as you said, I would think maybe JC Penny, Dillard's, or Burlington Coat Factory. They have nice clothing for both genders and they usually have good sales-at least in my area they do. Maybe American Eagle if you're willing to spend more if you're like cool, chilled out, or preppy.
Exactly what is your persona--outgoing, quiet, brash, laid-back, etc? Any interests that you can go on that you can build upon to make who you are without trying to change you on the inside?