Don't Give Them Names
Entering a room where a barbarian awaits us, donning his armour near a two-handed longsword, with a two-headed dog on the other side of the room, fills us with some level of pessimistic dread. Enough dread that the topic of new characters arises.
'The problem with needing new characters will be how to introduce them in to the adventure.'
'Oh, it won't be so hard', says the GM. 'You just turn up at Perrett's Fort and drop in.'
'Yeah, we're a band of renegades who...'
'Hey, don't give new characters a backstory. We're not dead yet!'