Get a calendar
You'll need a calendar with enough space, to enable you list out all your tasks. Try not to have different calendars for your activities; you can merge them into one, to avoid having one for school, and another for home and meetings. It can get you confused. You can use a notebook to make this happen, and can also make use of electronic calendars.
Organize your tasks
Organization is very important; it brings clarity and makes things easier for you. One of the benefits of using an electronic calendar is that it allows you add colors to your tasks, like giving all school-related things a particular color and doing same for other categories. If you are making use of a notebook instead, use colored pens, pencils, or highlighters.
Prioritize your tasks
Set your tasks on a scale of preference. It is important that you know which tasks are most important and should be done without second thoughts, and tasks which can wait. This will avoid you leaving the most important task out, or doing something shabby. You can also mark your prioritized tasks, either by numbering/lettering or using colors to differentiate the urgent ones from the later ones.
Schedule a time for each task
This is yet another step that can't be escaped. You should know how much time it'd take you to complete a particular task; you can decide to finish up two letters in 30minutes and study for 3hours. While you schedule your time, you should not forget to include transportation time, like moving from your home to the office, or school to home.
Leave some space in your schedule
Leaving out free spaces at the end of your schedule is also a part of planning; this is just for unplanned tasks that may come up later in the day or week that you might have to input later on.
Check your calendar
Form an interesting habit of checking your calendar every morning and night; morning, to know what you have to do for the day; night, to know if you accomplished your goals and what is up for the following day.
Check completed tasks and adjust your schedule
It is important that you finish up a task for a particular day, but then, some things that can't be controlled happens, and you might have to move some tasks to the following day. After ticking out completed tasks, see to the ones that were skipped, and adjust your schedule such that those tasks fits in to somewhere else.
Assess your schedule
It is very important that you check your schedule often, to know if it is working the way you want. If you figured that you keep carrying over tasks to the following day, and having so many spill overs, it just might be time to re-schedule.