As a wise soul said here once, "If this was rocket science or easily screwed up, they wouldn't allow us to do it ourselves."
also straight in straight out. give 15 sec or so before pulling out. i never had blood, bruising or any marks. good luck.
How much blood was there ? If a little it was a capillary no worries. Remember pinch your skin insert needle let go of skin then inject. Most of the time there were a few drops of blood when and always a red spot it was never blue.
That happens sometimes. It's nothing to worry about.