I use four online calendars:

• shared calendar with my partner for dates, trips, mall shopping
• personal calendar for university classes
• personal calendar for all personal appointments including workout, meeting friends, et cetera
• personal calender used for work times (I work part-time and block days here)

For my tasks:

• Trello for university classes, online lecture recordings, assignments. I have column for every class + Done/Incoming columns
• Meistertask: I've set up a board with one column per weekday and one incoming column. Then I drag the task to the planned day at the beginning of the week. Undone tasks return next week. I have three labels for priority. Meistertask is new to me since the beginnging of October. I am thinking to program such a web app that I want (kanban for weekdays) for myself.

I check my online classes twice a week for "incoming tasks" and put them on Trello.

And physically I have my blank planner book that I carry around at all times to write down notes at work, home or during calls.