If keeping regular to-do list (see previous post) is too daunting for you or it seems to be to big of a task then try this.
Out of the things that need to be done next day select three (not more) things that are most important.

Leave this paper with 3 things on your table and start working on them as first thing in the morning.
Don’t stop until you finished them all.

Then and only then you can start with other things
(yes, even email shouldn’t be opened. only in case there is something that would help you finish your 3 most important tasks).

If you’ll not manage to do anything else that day except your 3 things – no worries there – at least you have your most important things done and I am positive these 3 things represent 80% of the value you would add today anyway.