My current, extensive copy editing project reveals some of the most frequently occurring grammar and punctuation errors. It reminds me that I no longer have my grammar website up and that I had intended on doing more of that here. More and more businesses, and independent entrepreneurs, are trying to develop their own websites and blogs for promotion. While many readers won't realize a comma is missing, correct usage lends both clarity and professionalism to any written words.
To come when I find time...
compound words written incorrectly (check dictionaries or Internet sites)
commas around independent clauses, closing commas around parenthetical phrases, etc.