I wear a bra and panties every day. Depending on my shoes, I very often wear tights as well.
The #1 way I've found to hide bra straps is a sweater or jacket. Of course, I don't try to hide as much as some people do (and I'm *NOT* bashing those who do hide it).
Sometimes I do wonder if I (we?) notice things like this because we're looking more. I mean, who would *Look* for a bra strap on a guy, right? Of course, the truth is people miss the most obvious details, and pick up on the subtle ones as often as the other way around.