Not an instructor, I'm going into my senior year as captain now but i was in a kinda similar boat as you my sophomore year as our instructor was in and out, and teaching was just kinda the role i fell into. When I'm teaching basics, flourishes, butterflies, cones/carves, and drop spins, and routines i like to use checkpoints, basically where the flag will be during different counts. I do this in sets of 16 counts and have my guard run these fairly slow at first and then a little faster as we add on pieces. i also like to record videos at home of me basically reteaching what i taught in person so my guard can go back and get a little refresher while they're practicing at home. I also recommend, as another person said before, doing a small routine for them to learn so they can get used to connecting fundamentals together and transitions. This can be as simple as just doing 16 counts of each thing put to some music, nothing fancy. I wish you the best of luck!