To always print out on paper before editing. It is true. You really do miss things by just trying to edit on screen.
Not only to read (you love books, otherwise you wouldn’t want to write them so this really is no chore) but to do so outside of genre and to include non-fiction. Stories are sparked from ideas. Ideas come from what you take in. See doing this as feeding your brain and your source of stories!
Put work aside before editing it and then sending it. You pick up more errors this way as you come to your story “fresh”.
Read your stories out loud if possible. Even consider recording them via your PC. I do this for my radio scripts where the sound of words is almost as important as the words themselves. It’s also a great way of hearing for yourself whether your dialogue flows or if your words seem awkward, clunky.
Read writers’ interviews in magazines like Writers’ News/Writing Magazine. These can be very encouraging and give a huge range of useful tips.
Never be afraid to edit!
Make sure presentation of material is good (no coffee stains etc) and that spelling and grammar are up to scratch.
Try to have more than one piece of work “out there” at any one time. It can help cheer you up when the rejections come in knowing you’ve still got work under consideration.
The more you write, the more pieces you can get out there! Don’t just wait for one piece to be accepted before you try anything else.
Always have a good dictionary on standby.