Essays / Help, I'm new here. Is it okay to use parenthese around... [2]

Hello, I'm in 9th grade. I have to edit my essay on Heminway's style of writing and I was looking at a site with rules on using parentheses.

Being a pronounced follower of the "iceberg" principle, his sentences are often deceptively simple.

This is the only sentence I used parenthese around my words. Is it appropriate or does it just sound cocky?
The site says:
Unnecessary Quotation Marks
-Do not put quotation marks around the titles of your essays.
-Do not use quotation marks for common nicknames, bits of humor, technical terms that readers are likely to know, and trite or well-known expressions.

Quotation Marks for Words
Use quotation marks to indicate words used ironically, with reservations, or in some unusual way.

I think mine goes under "well-know expressions."
Comments appreiciated.