This might seem like a tedious chore, and to be honest it's not exactly a barrel of laughs, but it WILL help you to focus your mind and potentially keep you from wasting your life watching daytime tv.
Obviously, Post-It notes are great, but my preferred method is a text document on my pc. Write yourself a list (or several lists) of everything you NEED to do and then everything you WANT to do. Obviously, using the pc method you can edit it without the need for tippex, and move things around as your priorities change.
The need to do list is vital as it'll contain the boring but essential tasks like getting household bills put in your name, contacting the local council for your council tax 'single-person occupancy' 25% discount, cancelling any non-essential direct debits and so on. The want to do list is where you write/type all the 'fun' things which will prevent you from becoming a hermit, such as all the people you want to have coffee with this month, local events you fancy going to and anything else that floats your boat. Just because you're now single doesn't mean you have to hide behind closed doors...quite the opposite in fact!