I take the middle through restrictions and traffic islands, anything else is an incitement for drivers to squeeze past. You may as well attach a billboard to the back of your bike announcing 'come on, there's LOADS of room!' I'd rather they be annoyed than I be injured or dead through a slight miscalculation on their part.
The streets near me are packed with parked cars on one side and to be honest, they're the worst roads to cycle on (not much fun to drive on, for that matter), combined with the fact they're often (and pointlessly) used as rat runs (the main road is always going to be faster, you are going to meet something coming the other way). This morning some idiot was revving behind me until she finally got to roar past. And then stop at the end of the road, whereupon I – as usual – overtook her. Often, to be honest, I'll wave a car past, it's less hassle than having the prolonged proctological annoyance. There's usually a festival of giving way for approaching cars, I have noted that generally when we're in the car, people will acknowledge you giving way to them (sometimes there are entire politeness battles, no you go first, no you...). On a bike, if I give way, it's fifty-fifty I'll get blanked, presumably because my transport choice has rendered me subhuman. Some cars will simply come at you in the expectation you'll lose an entire dimension, I'll hold my ground if safe, but sometimes discretion is indeed the better part of valour.
I pull out way before overtaking parked cars, buses etc. and take the lane otherwise I find that approaching cars will still attempt to overtake even though it's clear I'm doing the same. I've tried to mini-indication to show I'm about to do this, and to be honest, it seems to encourage them to try a bit harder to overtake, like waving a red flag at a bull while calling its mum a cow.