How do you keep on top of your daily tasks, and medium to long term actions you need to take? How do you prioritise them? How can I make a proven system and make into a habit?

I usually begin the day with writing down what i need to get done. I then think of how much time I need for all of them and prioritize them according to their deadlines. If you want to stay on top of your tasks you can write down the things you need to do as soon as you learn that you have to do them.