A task list should enhance your productivity by offloading bookkeeping. That's it. If you need people to yell at you (as the OP says) to determine priority, you are probably working in a painful and interrupt-driven way.

Here's my method (for writing software):

  1) Blank sheet of paper (8am).
  2) Figure out one thing to do, and write it down on just one line.
  3) Finish that thing.
  4) Check that item off, and write down the next task *before you put down your pen*.
  5) Goto 3.

This is how I stay focused without trying to forecast too far into the future.