There's currently no way to put tasks into a specified order (ie if you have a list of tasks that all need doing today, but need to be done sequentially).
You can add a number to the beginning of each task and sort by task name, but once you hit 10 tasks, the sort order fails as 1 is followed by 10, 11, 12, etc.
Instead, add a time to your due date and sort by the due date.
You can have up to 1440 tasks in your list by changing 1 minute at a time.
What I tend to do is use the hours for each task (if I've less than 24 iteims on my list!), then I can use minutes to create sub-lists and still maintain order.
It can be a PITA to reorder them, I'd love to be able to drag and drop list orders, but it's better than nothing!