Should every post you create be posted in a community?
Yes. When we were on steemit, tags where very much useful since all post are categorized under those tags. There were no communities. But since Hive came along, communities became stronger and tags, although used, is only second to communities. So If you want your posts to effectively get to the right audience, you must post them in communities.
You also mention that you can use up to five tags, I regularly use 8 or 9, is this not good practice?
It is. I had to edit that part since we are allowed to use up to 8 tags on hive. Back then on Steemit, it was 5 maximum.
RE: How to make a post on the hive platform - for newbies!