When I'm not making an effort, I'm REALLY lazy clothing-wise. Jeans and t-shirts, jean shorts and t-shirts, or jeans and sweaters depending on the season.
When I am making an effort, I've found that the "classy elegant" look works pretty well for me. Basically, things which are a bit conservative, not very revealing (my arms are too big, I'm too overweight, and I don't have enough boobage to make any degree of "sexy" look work,) very bland classic types of colors, mostly whites, reds, purples, and dark blues on top, black or brown on the bottom, and clothes that mostly cover everything except for a v-neck.
I wish I could do more, but firstly I am really clueless in regards to clothing or originality or styles, and secondly I just don't think my body is made for it. My upper body is just too big and square to wear anything sleeveless or super-feminine. Sigh...