Melissa Donovan gives us 10 good reasons to learn a things or two about grammar (and I would add, punctuation). If writing is your thing, then this is something you should know about – you don’t have to be an expert – that’s what you rely on an editor for, but it will definitely save you money.
Because I base my fee on time, I do a test edit on all manuscripts I work with, so it will cost less to edit
an already well written (grammar and punctuation wise) manuscript.
If you want to take a grammar and punctuation course, check online or at your local community collage. I have taken courses online through Mediabestro in New York and I would recommend them.