Well, it obviously depends on the book. I would put in a lot of tags, as people will search for them if they like that topic, and an interesting cover. There is a cover shop that I use here on wattpad (free) by @aerope , and it’s really good. It can also take time to get readers, so don’t worry to much about getting readers. If you love to write the readers shouldn’t matter, but I know it feels great to watch those numbers go up. Also, people can be deterred if the chapters have bad spelling/grammar, as I found, but if it’s only a word here or there is fine, just make sure to proffread, or even see you you can find someone who edits book chapters her on wattpad for free (like me ).
Hope this helps, and never give up just because you don’t have many readers to start. They will grow!!