I completely suck at turn-talking, even when actively trying to anticipate when my 'antagonist' wants to say something. Does anyone have actual tips for improving this?
Looking away for a while and suddenly looking back with their mouth open slightly can also be an indicator. If they have their mouths closed tightly, they're deciding whether to interject, so you might want to check a sentence or two later to see if they've made up their minds.
And it's cues, not queues :-)
Also, consider where in a conversation you are- you should be taking shorter turns when you are just beginning to talk to someone. If a person asks you "How are you doing" or "What have you been up to lately?" you should give them a quick summary and then ask them the same question. This is assuming that it's a social situation where you expect a conversation- don't return the question if your boss asks you what you've been doing, and don't answer at length if the question is just a social nicety. The cashier in the grocery store doesn't want a detailed answer to "How are you today?", you should just say "I'm fine, how are you?" Hope that makes sense.