It depends. One thing that very very rarely happens is that an author will draw their own illustrations, because most writers can't draw. JRR Tolkien could draw and often did illustrations, he even made a book consisting of nothing but illustrations of Middle Earth - my point is that his illustrations added to the story and there wasn't anything too technically difficult. I mean, where would anyone reading The Hobbit be without that map!
So it depends on the subject matter of your story - it might not need any sort of illustrations, they might even end up detracting from the story if you don't have good continuity. If your story is about an adventure, then illustrations would be a no brainer for me - I'd do my best to draw a cool map and dimly lit caves and forests and monsters or anything relevant that can look nice. I'd use pencil guidelines then ink over the top and scan to end up with monochrome line drawings, as they translate really well when printed. Stylize, don't try and be a hero and use colour - not unless you have exceptional watercolour skills. And print the thing to some decent paper, your time and hard work is more valuable than normal photocopier paper
Draw anything you need at least twice - rough sketch, then a cleaner sketch that you adjust til your happy, then ink on top of that, taking as much time and patience as you can. Try and stick to a single dithering method, like even if your short story only has 2 or 3 illustrations, use the same style throughout. This is not only about producing a nice looking drawing - it's actually a lot easier to work this way... get's your ideas down quickly, then you refine them, then you make it permanent with ink. Take your time and consider the level of detail and lighting at all times. Ohh, and use a nice font - something you haven't used before but is still a fairly traditional typeface.
Also, try and make the story a good 6 or 8 pages long - a short story isn't about how quickly a story can be told, it's about how effectively it can be told. Plan the story first, break it up into chunks and then 'pepper' the details onto that organically. Don't just start at paragraph 1 and keep going til the end - consider your brain as a resource that tries to output it's best work first - so spread that around the whole story by planning and considering different parts that have a real impact on the plot rather than spending it all on the first page.
Good luck - I think you'll enjoy it, heck doing stuff like that was the only part of English class that I liked, appreciate the fun aspects of your classes and make the most of them I say, they are often the most relevant and useful lessons in the long run. And don't worry too much about the illustrations, your English tutor won't mind if you can't draw - but if you spend time making your story interesting and easy to read, they'll sure as heck notice that. Personally, I think you WANT to write an interesting and exciting story and have nice illustrations to go with it - so go for it and don't dwell on lack of skill, concentrate on how you can make the most use of the skills you have.
This is all overkill, no doubt it's a lot more than your tutor would expect - but hell, it's a short story - along with being an English class assignment it's also a thing in it's own right and maybe deserves some special attention and time. You won't remember all the math problems you solve or the science experiments or exercises or anything else nearly as much as you'll remember the short stories and writing exercises that you'll do.
Just my... lets call it about 27 cents
I am the one who knocks...
