most common mistakes? i can list it. most of them are from my own experiences :
-Have no idea about market demand. not all our niche has a good demand.
-Keyword planner. Have to learn how to use it. If we want to get good ranking-SEO, then keyword planner
will help for starting
-marketing. most of starter think that after posting a few articles, traffic will come easily without any
marketing task.
what I learn from others and my own experiences, keep posting content everyday and active in social media
will help.and the content should in high quality type with unique writing...
consistent will all of the tasks(writing,posting,sharing bla bla..) we can see a positive result at least in 3-6 months.
If you use paid marketing like adwords,Fb ads, you can earn ROI faster....