I use A-shirts myself. In this climate, wearing more than 2 layers of clothing gets hot. I pretty much use them as a mask for my white shirts, so it doesn't look as if I'm not wearing an undershirt. T-shirts under dress shirts in a temperate climate with a suit or sport jacket are overkill, especially if you're not in the habit of removing your jacket. You'll heat up and sweat more with a t-shirt. When dressed well, I use sock garters. Nothing ruins the look of a good pair of socks like having them bunched up at the ankles.