At the end of each day, before you finish work and relax, make a list of all the tasks you want to complete the next day. This way, when you sit down at your desk the next day, you have a clear picture of what you need to do which gets your day started in a highly focused way.
Take satisfaction in checking off the tasks as you complete them, allowing you to track your progress through the day and keep you focused on your priorities. You might want to keep your list for the next day handy and add in tasks as they come to your attention throughout the day.
There are a whole range of apps and integrated to-do list services available if you prefer to keep lists digitally. Otherwise, you could use a dedicated notebook that stays on your desk and contains all your lists.
Bullet journaling is a great technique for keeping track of tasks over time while generating lists for yourself in a way that keeps them organized and quickly accessible.
Check out this short video (4 min) that will introduce you to the concept of a bullet journal and how to begin.