Show don’t tell - good description is crucial. It sets the mood for the entire piece of writing. Having said that, too much description is distracting and is boring to read. Pick your words carefully, and add plenty of detail, but not too much. It is too confusing to read.
E.g. The girl's face was pale in the oversized mirror above the white sink that was hanging from the far wall OR I got dressed for the day. I had a flowy pink top, and denim shorts, with a silver necklace and my pink and white strappy sandals.
It just becomes too much - like looking at an overly cluttered room. Your brain can't handle that much information at once.
Pet peeve alert: I really dislike it when an author says 'jean shorts'. Jeans is acceptable for a pair of jeans. If you have a pair of shorts made of the same fabric, then they are called denim shorts. Maybe it's an Australian thing, and other countries genuinely call them jean shorts (please correct me if that is the case), but it just sounds silly to me.
Spelling and grammar are immensely important.
Spelling errors - having the odd typo is fine. I’ve seen them plenty of times in professionally published books; but when they start to become distracting, then it becomes a problem. PROOF READ. I can’t say it enough. A teacher that I had back when I was still in school once said that the best way to proof read your work is to read it backwards, because then your brain can focus on the individual words, and you will be more likely to pick up mistakes.
Grammar - this bugs me more than spelling errors. It is very difficult to enjoy any story if you can’t understand what the author is trying to say. Again, this is fixed with proof reading your work. Perhaps you can read your work aloud to yourself, just to see what it sounds like. If it sounds like it is not making a lot of sense, then you may need to go back and revise a few things. Reading it to another person also helps, if you have to courage to do so.
If in doubt, do not hesitate to ask someone for help. Look up words in a dictionary or a thesaurus. Ask someone to proof read your work before you post it.
Post your work on more than one website like I have. You will be surprised at how the audiences vary between different websites. What is popular on one website may not be on another, and vice versa. I also post when I know a lot of readers are going to be online to see the update. From stats on various websites, I know that the majority of my readers live in the USA. This means that I post my updates when it is late at night for me, but early in the morning for them. More people are awake to see the updates, and over time I have found that I get more reads like this. There is no point in my posting an update during my lunchtime, because that is when the rest of the world is asleep. This will vary depending on where you live, and who your main audience is.
The more polished and professional your work looks, the more likely it is that someone will want to keep reading and enjoy it.
I always encourage readers to give me constructive criticism. Of course I appreciate all the lovely comments that I get, but at the same time there is a part of my brain that is begging for someone to tell me what is not good about my book. I want to know what is horrible about it so that I can work on improving it. Often I am too caught up in my own head to realise repeated mistakes; or in some cases I have been misinformed/confused about facts. It's fine to tell me when I'm not doing a good job. I won't get mad as long as it is about how to improve my work as opposed to a personal opinion. Telling me how much you hate Hermione and Sirius together does little to improve my writing and characterisation. The same applies to any author, or indeed any person who is commenting on a book.
PLEASE DON'T HESITATE TO ASK QUESTIONS YOU MAY HAVE ABOUT WHAT I'VE WRITTEN, OR WRITING IN GENERAL. I DON'T HAVE ALL THE ANSWERS, BUT I CAN CERTAINLY DO SOME RESEARCH AND FIND OUT :)