While we are on the subject of grammar, I should make my case clear - or rather, I should have W. Somerset Maugham make my case clear:
"Only a few years ago, I was spending some weeks in London and had engaged as temporary secretary a young woman. She was shy, rather pretty, and absorbed in a love affair with a married man. I had written a book called Cakes and Ale and, the typescript arriving one Saturday morning, I asked her if she would be good enough to take it home and correct it over the week-end. I meant her only to make a note of mistakes in spelling that the typist might have made and point out errors occasioned by a hand-writing that is not always easy to decipher. But she was a conscientious young woman and she took me more literally than I intended. When she brought back the typescript on Monday morning it was accompanied by four foolscap sheets of corrections. I must confess that at the first glance I was a trifle vexed; but then I thought that it would be silly of me not to profit, if I could, by the trouble she had taken and sat me down to examine them. I suppose the young woman had taken a course at a secretarial college, and she had gone through my novel in the same methodical way as her masters had gone through her essays. The remarks that filled the four neat pages of foolscap were incisive and severe. I could not but surmise that the professor of English at the secretarial college did not mince matters. He took a marked line, there could be no doubt about that; and he did not allow that there might be two opinions about anything. His apt pupil would have nothing to do with a preposition at the end of a sentence. A mark of excalmation betokened her disapproval of a colloquial phrase. She had a feeling that you must not use the same word twice on a page and she was ready every time with a synonym to put in its place. If I had indulged myself in the luxury of a sentence of ten lines, she wrote: 'Clarify this. Better break it up into two or more periods.' When I had availded myself of the pleasant pause that is indicated by a semi-colon, she noted: 'A full stop'; and if I had ventured upon a colon she remarked stingingly: 'Obsolete.' But the harshest stroke of all was her comment on what I thought was rather a good joke: 'Are you sure of your facts?' Taking it all in all I am bound to conclude that the professor at her college would not have given me very high marks."
The above appears in Maugham's The Summing Up, which he wrote in 1938 at the age of 64. Cakes and Ale was written in 1930. Maugham's first success with writing was with Liza of Lambeth, which was published in 1897. Between those last two dates Maugham became an insanely successful playwrite and wrote a great many books, including The Razor's Edge, The Moon and Sixpence and Of Human Bondage.
As such, the complaints and perturbations of grammarians should not be taken too much to heart. The motivations behind such people have very little to do with the creativity of language, as their main focus is to put a straight-jacket on language, gag it and drop it into the sea. If you have been told by an English teacher, professor or expert on letters that you have no talent, congratulations. You have just proved that in 80 years, grammarians have not changed a bit.
There is one purpose for grammar, and that purpose is to make yourself understood. There is great sense in grammar in that one ought to know the placement of commas and other devices, if only to clarify examples such as "Eats, shoots and leaves," as the famous book sets out to solve. No question about it, knowing where paragraphs go is helpful. As is knowing virtually every other rule you can wrap your head around. It is a cliche, but it is a serviceable cliche: learn about grammar's rules, and THEN break them.
You will read things written by people who will tell you to reduce the number of ellipses, colons, semi-colons and dashes in your work. An editor will not turn you down for such things unless they are so abundant that its impossible to read what you're saying - so yes, try to keep them to a minimum. This does not mean that you should not use them. Use them sparingly. When you are wildly famous and successful, you can use them abundantly and to your heart's content ... but I'm guessing by then you won't want to.
Similar things can be said about the length and type of sentences, the old bugbear about prepositions, comma splices and so on and so forth. Sit down with a book and learn what they are, and learn how you are abusing them. And then, after you've come to a decision about it, throw away the book.
I repeat for emphasis. Be clear. Write in short, direct sentences. Reserve your long, developed sentences for when you feel comfortable, or even resolute, about saying a particular thing with a certain pomposity that fits with your character. Mix it up. But most of all be aware of the sentences you are writing. Know when you've written on and on in some absurd irrational sentence with no proper punctuation or clarity that leaves your reader unsure about what it was exactly that you were trying to say when you started the whole thing off. The more you know about your own writing, the clearer your writing will be. And the less guff you will have to take from so-called 'experts.'