I am not sure I can give tips because I am about as unpublished as you can get and if I knew how to be published, I would not be here hoping to get something right for a change; therefore, I will keep this as short as possible. I did self-publish a Bible Study - it is great, although after it was published I tended to disagree with most of my views. Still, it does have a very attractive cover designed by the publisher and paid for by me. I also noticed that there are used copies for sale on Amazon - if I never sold any, how can they sell used copies?
I have had somewhat of a writer's block for four years now, but I put a humorous diatribe on Amazon Kindle. No one has purchased it, but being optimistic, I think it is because no one can afford the Kindle; I know I can't. So there it sits, unread by everyone but me.
I am a grandmother and have purchased several little toddler books for my grandchildren. Wait, I can write one of those, there are only six words in the whole book; the downside is that I have to know how to draw cute bunnies or some other animal that does some cute six-word activity. Actually, I used to be able to draw; I did a pastel of Harry Belafonte in high school - it was wonderful. I framed it and took it with me everywhere I moved. Unfortunately, my second husband was jealous that I had a framed picture of a black man on our coffee table and none of him, so I put it on the closet wall to make him happy. It eventually disappeared and I know he put it in the fireplace when I wasn't home. We did not get a divorce over it, but there is a sizable wedge between us and now he is the subject of whatever stupid-husband humor that I write.
Getting back to tips; I have come to the conclusion that if you are not totally insane or a celebrity that has had a shady life, you are not going to get published. Many of my stories are just as good as Stephen King's blood-lettings or Nora Robert's lovemaking, but no one cares because I have not run naked up to the President and accused him of fathering my child (which would be hard to believe since I am old enough to be his grandmother). It may just be crazy enough to get a publisher interested in something I have written - too bad I am shy about exposing my horrendously ugly body, but others of you may not be, go for it, that is the best tip I have at the moment.