7….
>> WHERE hash_column = MD5( CONCAT(col1, col2) )
>> AND col1=’aaa’ AND col2=’bbb’
This will cause full table scan every time, if no indexes for `col1` and `col2` specified

14.
>> … This reduces the query parsing time.
It is cost nothing compared to data insert & index rebuild on insert.

… and there are few tips added by me
0. ALWAYS use EXPLAIN query on each query that doesn`t use PRIMARY KEY (eg. SELECT … FROM … WHERE id=…)

33. Don`t use NOW() or CURRENT_TIMESTAMP() – it is flushes query cache

34. Avoid of using ORDER BY .. DESC – it is always create temporary table.
Use default/ascending order in any cases where it is possible.