Take a book – any book will do, though a really well written one will be best. Open it at random. Find a phrase or sentence or word that appeals to you. Write at the top of the page. Use that as your inspiration and guide. And then… write.
The quote as starting point is quite a well used trick. Look at those authors who put poetry quotes at their chapter headings. Or all those books with titles from Shakespeare, or the Bible (use the King James version. That has truly beautiful prose).
That one line can be enough to kick start your imagination. Maybe it’ll suggest a situation or a place to you. Perhaps it will give you an insight into the way a character thinks. Maybe an entirely new plot spun round that one phrase.
Mind you, it doesn’t have to be Shakespeare or the Bible. A lot of Agatha Christie’s book use a Shakespeare quote as a title – but a lot of her books also use a nursery rhyme. (Nursery rhymes are good – we all remember them, we’re drawn to them, but they also often have sinister connotations).
It doesn’t even half to be a well-known quote – just a phrase will do. One of my fanfics was inspired by opening up Alice in Wonderland and finding a random sentence that exactly fitted.
Good books and authors to try are: Wind in the Willows, any Raymond Chandler book, Alice in Wonderland, any kind pf poetry – in fact any book that you believe to be beautifully written.