When you read about grammar, you are constantly reminding yourself about rules that you may have forgotten about. It’s always a good idea to brush up on the rules. For example, the 7th rule in the third edition of Elements of Style is to use a colon after an independent clause and before a list (Strunk 7).
Sometimes grammar can be used in multiple different ways. Especially with participle phrases, you need to be really clear about what you are referring to.
In both instances, the punctuation is correct but implies different things. You should be able to explain why you chose to use or not use commas.
When you understand grammatical concepts, like how to remove negative phrasing and how to prevent comma splices, writing becomes a much quicker process. You stop questioning yourself on how you used punctuation because you are sure about your choices.
Grammar is not just a set of rules; it helps communicate a message. When you understand how sentences and paragraphs are crafted, you can truly communicate effectively and succinctly.