Punctuation. You need this book by Birch Leaf’s Sue Feehan

Sue writes: Pesky punctuation marks throw themselves at your feet daily, like cats begging for a belly rub. You long for a way to avoid the troublesome devils, but you have to write as part of your job or studies. And you need to organise your words somehow... So you smile and indulge the belly-rub fiends as the safest option. Except reckless indulgence could land you in court, forced to argue unsuccessfully that a comma can't possibly make $2m-worth of difference to the meaning of a contract. Impossible? All too possible. Far-fetched? It's happened before. Take the sad wretch who forgot to use a vital hyphen — and a space probe had to be exploded to save lives. Or the poor soul who left one out of a nuclear plant order, creating a radioactive mistake that had to be buried for decades at a top-secret cost. Your career could start to circle the plughole thanks to a belly-rub devil... You don't need charts, graphs or academic lectures that make you feel stupid. You want jargon-free guidance, useful examples, and advice on how to ignore 'the rules' when it makes sense to do so. Here it is. Becoming a punctuation wrangler won't make you a great writer. But it's a damn good start.