I have two habits which I know are the most beneficial to me when I'm at my most productive with my fiction writing. One I have heard several times in various contexts - in writer's groups, on courses, in books - whilst the seconf I think is one of my own. I don't remember hearing it anywhere else but, like many things, I might have unconsciously picked it up.
The first beneficial good habit is to set a time every day when you will write something and stick with it. No excuses, just do it. Sometimes it's painful, you know you are writing rubbish and it seems pointless. Whatever, the more you get into the writing habit, the easier it will be. Write a 1000 words a day and in 70 days you have a decent sized novel. This has to be the number one tip for any writer (and its the one I'm breaking at the moment - I will have to stop making excuses to myself). I managed this every day for 5 years and the output I created was fantastic.
The second tip is the one that might be mine - At the end of these regular sessions you will find that you are in the flow, that you know what section/passage/event you are going to write next. When you get to this point, stop before you reach the end of the piece you are writing.
This might seem counter intuitive - surely the whole point of this regular writing is to reach this 'flow' point? Well, yes, but you will find that, in the long term, this will be really beneficial. One of the great difficulties that most writers find when starting a writing session is getting going. If, when you sit down, you know what you are going to write first you will find that you will get into that flow much more quickly. These times for writing are precious and often short, you need to make the best of it and I have found - for me - that it is this trick that works best.
Try it. This may not work for everyone but I have found it really useful.
And I must take my own advice because I have strayed into bad habits....!