Remember: editors aren’t thinking about you.
I once read a quote – I wish I could remember who said it – that’s stuck with me for years:
Don’t worry about what other people think of you. They’re not thinking about you at all. They’re thinking about themselves… just like you are right now.
"Confidence" is overrated.
Over the years, whenever I've told myself that I lack the confidence to do something or other, it usually means that I don't want to do it... or I'm lazy. Too lazy to put in the time to LEARN how to do it, and too stingy to "waste" time. (No time you spend writing is ever wasted, it always teaches you something.)
Words to live by if you're worried about what someone will say or think about your writing -- NO ONE CARES. No one cares as much as you do.