Giving step-by-step instructions is great. Giving theoretical explanations is great. But ultimately, the student's going to be doing this without you, so it's important to find out how much they're understanding.

There's a simple way to do this: periodically ask if they understand, accept a murmured "sure," and keep going. Resist the temptation. "Do you have any questions?" is better; best of all is to give exercises.

These don't have to be lengthy, or even pre-planned. Say you've just walked someone, step-by-step, through changing the side margins on a Word document. After applying that change, ask them to change the top margin to 1/2" and sit back.

Even if you (and they!) thought they were following perfectly, there's a good chance that you'll have to prompt them at least once before they're done. Do give as much help as they need, but no more than that. Unless they start getting frustrated, don't start walking them through again - give them a chance to remember each step on their own. Afterwards, give them another little exercise.