In your informal writing do you put punctuation inside or outside quotation marks?

When quoting another work I like to keep my punctuation marks separate from the original work. MLA style requires that I put punctuation inside the quotation marks, so I comply, but it drives me crazy doing so. In my opinion, my added punctuation isn’t what the author intended so it should go on the outside of the quotation marks. In all of my informal writing I do this.

So, how do you like to treat this in informal writing when you aren’t held to certain style standards?