Don't worry about the dagger strokes. It's a pretty specific technique and as such you won't need it that much when starting out (its nice to have mastered it when doing fur though.. on the other hand fur is a nice way to master the dagger stroke
).
The problem with the dagger stroke is that it more or less combines a lot of techniques (line, fade, in/decreasing paint, in/de creasing distance). As such it's a excelent practice method to get trigger control but I wouldn't start with it till you have a firm grasp of putting down lines consistently (as in have them start where you want them and them having the width you want them to have). When you have a decent control of that the dagger strokes are the next step.
Don't try to learn everything at once as that will soon become frustrating. the order which I generaly advice:
-Fades in a square (horizontaly, verticaly, diagonaly)
-Fades on a ball (changing the light source a couple of times)
this should give you a feel for the amount of paint and spray pattern at a distance
-Dots
Learning to aim
-Fade on dot (make it a little star)
Learns distance and in or decreasing the amount of paint
-Lines
When does the paint start what effect has speed, distance and the amount of paint
-Lines that follow a scribled line
General control
-Dagger strokes
Combination of most of the above
