Mistake number 5 is not knowing what the alias field is for and how to use it to your advantage.
You can find the alias field on articles, menu items and other extensions. It usually comes right after the title field.
The alias field allows you to control the words used to create the search engine friendly (SEF) URL.
If you had an article with a very long title, the SEF URL would also be long; it would contain every word of the title, making explaining access to a page on your site difficult.
The alias allows you to enter exactly the words you want to include in the SEF URL. You will be able to keep the URL short and include the relevant keywords.
Joomla automatically creates a default alias when you write an article. Replace that alias with your own short version that includes keywords.