Economic vs. EconomicalHow to use "economic" and "economical" correctly
The word economic describes things having to do with the economy; something economical is inexpensive or efficient. Although economic can be used to describe someone who is thrifty (careful and wise in using resources), it’s better to use economical in such situations.
an extremely economical lifestyle in which nothing is wasted
Common Errors in English Usage: Errors in diction and idiom commonly made by native speakers of English
List of Common Errors in English Usage (PDF): Printable version of the complete list
Common Grammar Errors: A list of common errors in grammar (topics like subject-verb agreement and parallelism) as distinct from usage