How do I improve my personality?

I am a high-school student, and I feel like my personality and social experience is blatantly more shallow than most of my classmates. It seems that I tend to stay indoors while other people go outside more, whether alone or with friends and family. This blandness also seems to be affecting my attire and general fashion sense, as I wear more monochromatic and dulling outfits when compared to others in my school. When I try to change, it often feels like I’m either copying somebody else, or I’m trying too hard. I constantly feel like I can’t make genuine connections when trying to make friends, so how can I gain a richer personality?