@ereinbergs I used Todoist for to-do list but recently I bought myself a whiteboard and I am switching back to that.
I also track my time using Toggl Track. I found that extremely useful to balance different activities and also to have a pragmatic way to decide what to do. I can say "Sorry I spend x% of my time doing xyz, I can't take on zyx as well"
Learning to sometimes say no to people is essential
And yes, if I need something done, I would block my calendar, allowing maybe 25% extra time for it. You need to learn to stick to those blocks.
But most importantly, if you didn't have time to do something... remember that the world is not going to end. Weekends are for resting, those things can wait until Monday.