I'm weird. On the 26th I'll be celebrating 13 years since going full time. Even after that time, I've worn exactly 3 dresses, none of which were my choice. I have a bridesmaid dress from 2004, a black dress for a funeral, and a cute sundress from a trip to Hawaii.
Generally speaking, I'm in scrubs at work, and in shorts or jeans with a comfy tee during the evening/weekend.
In my opinion, especially in the early transition days, jeans were my best friend for "passing." Many people assume that all M2F trans people are just extreme cross dressers, so they're much more critical of someone in thick makeup, a frilly dress and hooker heels shopping at Safeway than a plain jane in a pair of jeans and a tee who looks like she's tired after a long day at work.
I studied women my age who share the same interests and participate in the same activities, watched what they wore, and did the same to "fit into the norm." MANY women never wear dresses, and putting one on may be what outs you more than anything. (Admittedly, my wife was also instrumental in helping me to dress appropriately)