The problem with learning to manage your time, is that the occasion when you need to learn is the occasion when you can't spare any time to learn complex time management methologies.

IMO, the key skill to learn for time management is the setting and re-evaluation of priorities. Look at what you have to do, rank the tasks by urgency (based on criteria like: making me some money, keeping me out of jail/trouble with Inland Revenue, meeting my commitments to customers), and allocate amounts of time to different tasks depending on their priority. It takes a little bit of practice, but not too much.

When the status of a task changes (bailiffs knocking on the door/final absolutely the last deadline for paperwork/critical bug taking your customers system down) re-evaluate the top half dozen tasks .

You can do this on paper to start with - after a while IME it becomes a habit that just happens, and you have a good idea of where you are at any given time.

One other thing: don't spread yourself too thin. It takes a little while to shift your attention, if you try to allocate 5 minutes to 96 different tasks for the day, you won't get anything done.

There's also a couple of tips I've always found useful on time management in this node from a few days ago.