I've had to do lots of that human tripod stuff (handheld and steadicam), and it's what a lot of hacks want these days (or that motion is gonna make that lame boring corporate shoot look more interesting, etc...etc...)... I haven't done the tennis ball thing (which I'm definitely gonna try now, thank, Stuart)...but often I'll put it on a tripod with it intentionally out of balance...and operate with a couple fingers on the handle instead of my whole hand so it kind of moves around, and I'll sort of shift my weight around or dance my fingers around a little bit so it'll get out of balance a bit and I'll have to correct it. It gives them that look they want (eye roll), but without killing yourself. Depending on the situation, it gives them that look *better* than a long take on a 50mm handheld b/c you will begin to lose control several minutes in, and then the look becomes the look of the person behind the camera struggling, which takes you out of the story, which is the opposite effect they're usually going for in the first place.
Another thing, get in the habit of just pulling it off your shoulder right after cut and hand it off. You shouldn't even have to really look, or have to ask. The good AC's understand this and are quick on it, but a lot of lesser experienced AC's aren't. Get that established at the very beginning, if they aren't doing it automatically This is a huge thing on something that's several days long, all handheld...it's a compound effect. It's a big the also b/c at the end of the take, you're tired...and the act of taking it off your shoulder means putting the weight further away from you where leverage is against you so that's where you're more likely to strain something. Even thou a top handle is more weight, I always have it for better handoffs.