Coffee cups almost all have a fatal flaw; there's a seam running up one side, and more importantly, it continues _into_ the lip of the cup. Why should you care? Because this small asymmetry in the cup's design creates a natural opportunty for hot coffee to sneak through the crack and drip down the side of the cup.
The solution? Simply rotate the lid so that the opening you drink from is _opposite_ the seam of the cup; this means that you'll be tilting the cup _away_ from the seam instead of into it.
You may not believe this can make a difference, but believe me I've been burned (in some cases literally) enough times to know :)

