Read constantly and widely - including stuff you may not like (or think you like), but writing is 60% reading, 40% writing.
Write every day, even if it is only a couple of hundred words. They'll soon stack up and your craft will improve.
Don't edit/re-write till you have finished a draft, no matter how great the temptation.
Keep the faith and remember that no-one else has your idea or your way of seeing the world. Don't worry if your voice on the page looks different to how you imagined - because that is exactly what will make your work unique..