So this bit is all to do with other writers

If a writer has written something of their own, don't go and steal it like a moron

If you want to use other people's work, be it a sentence or the whole thing, ASK FOR PERMISSION, but be specific

If you've asked for permission and they've said yes, then great, we can move on to the next bit

If they've said no, then don't threaten them or anything, don't be a muppet, just suck it up and write your own work, and do NOT use their work anyways

Once (or if) you've got the other writer's permission to use their work, C R E D I T T H E M

There's nothing worse than seeing your work being passed off as someone else's, so don't be a dickhead by doing that