Great post, @jonsnow1983.
Hope you can post enough issues in this series to compile a book :)
This kind of brief and clear tips are always useful, even for those who already speak some English.
One case that always intrigued me is the use of the article in words such as historic/historical
it should be a historic/al
and yet, there will be instances where we'll see
an historic/al
most will say it is because of regional tendencies to silence the initial h.
Another explanation may be to avoid confusion with words like ahistorical (that carry the negative prefix a)