This is just based on personal experiences so take them with a grain of salt. Also, huge sarcasm ahead. Hope this helps a lot of folks out there:
1) Inconsistent updates.
I am talking about those who takes weeks or months without even talking to your readers. They may drop a chapter anytime this week, going on hiatuses as everyone wonders when you're gonna come back.
I get that you have life outside of Wattpad and sometimes need to take a break, but at least say "Hey, I might be gone for a while so expect to get an update around this date ... " and provide a recap like how a lot of cartoons do at the start of a new episode.
2) Voting or commenting on your own works.
Not only is it weird, but also shows how dishonest you are with numbers. It's the readers' job to comment and vote your book. I'm not surprised if someone also used bots to give them many votes and followers like on other social media sites.
The only thing that I might give a pass is if you comment clarifying something or leaving some notes. Just don't comment saying "My book is so perfect and now I am on top of the algorithm BRRRR!"
3) Bad edits and grammar. Period.
I have seen books with poorly-edited covers, super loooong paragraphs, random images, bad grammar, spelling and bad placements of punctuation marks.
Sometimes, I see dialogues being written in bold letters for no reason (unless it's geared towards readers with dyslexia who struggle with fancy fonts or italics). Not to mention that authors would brag about not even making any edits ar all on their bio.
I also remember how people find it weird that my books tend to have italicized dialogue but that's just my own style and helps set them apart from the rest of the text.
4) Poor marketing.
Man, don't you just hate it when an author baits you on checking out a chapter that's supposed to keep you on edge but later see it's a different one?
While there's nothing wrong with overexaggerations and keeping things short to avoid spoilers, be a little honest with what character events are actually gonna be in your story. Everybody is gonna think you're a fraud and stop giving you any chances.
Also, don't pester anyone to read your books 24/7 without knowing if they actually accept book requests or not.
5) Constantly stirring drama.
Drama ain't a good marketing! I repeat, drama is not good. Nothing pisses me off but letting your fans attack others, stalking them, getting someone cancelled for their differences and constantly throwing shade at other authors for clout.
Think about what your potential employers, family, friends and even teachers are gonna think (unless they know your real identity).