One of the big problems writers have is to write with clarity so that their reader is not confused.
As writers, we know in our mind what is happening in a scene, whether it is fiction or memoir or personal essay. Or even poetry. Because we see it so clearly, it's all too easy for us to skip over details that help the reader also 'see' what we are writing about.
If I'm writing a short memoir piece about my childhood years, I have a mental picture of the big apartment buidling where we lived. I know there is a brick street that runs in front with the tires of cars bumping along. I know that across that brick street, two sets of railroad tracks allow both commuter trains and freight trains to rumble by. If I don't add those pertinent pieces of information, the reader can't tell what kind of neighborhood I lived in.
When I write about my grandmother, I know that she wore her hair in a braid wrapped in a crown atop her head. I know that she wore rimless glasses, orthopedic shoes and an apron when she cooked or baked. I know that her expression was often stern and her words sometimes cut straight to the heart but that she had a soft spot, too. My reader doesn't know it unless I include all that in my story. I don't mean writing a paragrpah 'telling' it either. 'Showing' is going to bring a clearer picture of her.
Use too many pronouns in your writing and the reader can become confused over who you're referring to. When you edit, watch for that. The same goes for dialogue tags. We don't need to use them in every piece of dialogue but if the conversation goes on too long, the reader can become befuddled so use them enough to make sure the reader is aware of who is speaking.
The poster at the top left makes an important point in a few words. Many writers have marvelous ideas but transferring from mind to the printed word is not always easy, just like the poster on the top right tells us.
When you edit a first draft, go through the entire piece with one question in your mind--Is this clear to the reader? Don't consider anything but that question for the first time through. Then check it again to catch other problems like redundancy, poor grammar, typos--the mechanical errors.
Whenever you write, be conscious about making sure you have written clearly enough so the reader is not scratching his/her head wondering about this or that.