Just realized there is an iPhone feature that lets you take multiple pictures in rapid succession. What's nice about this is you may get a couple of good ones while with the standard one shutter click you only get one and if it's bad, the scene you've shot is probably gone.
All you have to do is hold down the button rather than shoot once and let up. It's called burst but isn't labeled as such anywhere. It really works. Kind of good for kids and pets where being still isn't often an option. Or group shots where often one person is looking down or blinking. This way you have a choice of the best ones.
When you want to delete a bunch of the bad photos at once rather than go through the individual delete process, just go to the camera roll, hit select and by touching each of the pics you don't want you, a check mark will appear. Then punch delete and they'll all go away.