I also use a Today card, but mine is a lot more intricate

I keep a template in Pages (the Mac equivalent of Word) and each Sunday, during my weekly review, I print seven cards (one for each day of the upcoming week).
This card has blank check boxes/spaces for time-sensitive tasks (i.e. meetings) and 10 MITs for each day. During my weekly review I look at my calendar and fill out the time-sensitive tasks, and each evening I choose 10 Next Actions and put them on the next day's card. I don't have a firm formula but I try to pick a variety of tasks, not all for one project.
If there are any large tasks with firm due dates (rare for me), I chunk it down and work backwards from the due date, so I know exactly how much needs to be accomplished each day to achieve the goal on time. I can also make on-the-spot decisions to put off chunks until tomorrow, knowing how that will affect the big picture, or quantify working ahead. (Lots of people work ahead enough for one day's worth of work and assume it was a week's worth of work, then get behind.)
If I have a Big Goal (like "Speak German fluently") that has a dedicated spot on my card so I make sure I accomplish at least one Next Action towards the goal each day.