Instead of "soft curses" I tend to employ "anti-curses," or epithet-based phrases that actually improve my mood. "Summon a beach" is probably the most common, and "shite" makes me giggle a bit. Come to think of it, "shizniblet" is something I tend to say recently, but never actually transliterated before
Don't get me wrong, I'm not Ned Flanders. When the situation calls for cursing (and often enough when it doesn't necessarily), I curse. It sometimes feels like Butcher, and by extension, Harry, have only come to that accommodation in the last 3-4 books.