Get a really good diary or organiser. In fact, you might need several in addition to a great big wall planner! The wall planner is good for seeing your year ahead (which you’ll need for planning all of your training, conferences and internships months in advance).
I mention multiple diaries because I use one for planning what I need to do, while I use the other one to jot down what I’ve already done. When you are writing several chapters or reading for several themes simultaneously it’s easy to lose track. Keeping a note of what you’ve been doing (and why) comes in extremely useful for dipping in and out of tasks efficiently.