look into something called a kanban board. Consider segments of:
Where a task X seems hard, break it down into smaller tasks, (task of break X down to smaller tasks)
As a bonus: make an estimate of how long each task will take. After completing - compare your predicting ability and update your time-guess methods.
I'm not sure how is this relevant to my comment. I do use Complice for what you're describing, but the gist of my comment is that the need for the reminder of "single task doing right now" to be in the field of view, lest it's not getting forgotten.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.