I'm SW developer. I met a guy who wants to help him to build an Android application from scratch. He does not know anything about it and he has to do it for some lecture at university.
I have no idea how to charge him as I will probably start with very general stuff like setting up tools (Android Studio) and we will probably not touch the actual task for a couple of lessons.
I don't want him to feel like he is not getting any closer to the goal so I don't know how to approach this issue.
I have done stuff like this before, and usually charge the client by the hour. It feels wrong to charge them my usual ("developer") hourly rate, so I've almost always lowballed myself and charged them much less. YMMV. (Especially if they are an educator, they almost certainly can't afford my rates anyway, but it feels good to "give back".)
I would just be clear up-front that they may not see much progress the first few sessions, and that this is a complicated topic that takes years (or at least 100s of hours) to become proficient.
One suggestion: Especially if they want to get more of the actual development, I would set a number of minutes you will devote to setting up their environment per session. Maybe only 10-20 minutes. When you haven't got it set up yet at the end of that time, switch to your machine, so they can see what development will be like once they've got the environment set up completely. Then finish setting their environment up next time. Or another thing I've done (although had less success with) is to send them links to try to get them to set up the environment in advance of our session themselves. Then you spend the first 10-20 min. trying to troubleshoot that.
Worth noting that setting up an Android environment (specifically w/ Android Studio) has gotten noticeably easier in the last few years, so you may (possibly) find yourself able to set up their environment in less than an hour, depending on a bunch of other factors.
What to charge.. I can't say. In fact no one can, really. It's up to you to determine your rates.
How to charge may be a different matter. Realize that one-on-one training is a premium.
If someone merely wants to learn something there are always dozens (or hundreds) of online tutorials, college courses (even community college), and online video training packages. These could all be utilized by the cost-conscious consumer. Getting direct, interactive, personal, training from a professional in any field is a premium service. There should be no discount for this service even if it's not your standard service.
If it were me, I'd charge my standard hourly rate regardless of what may be the topic of training. This is done because my rates are set to cover costs for my time, not for that I'm doing during that time period. While it may be true that there is much less overhead in teaching, compared to directly creating something, the overhead charges built into any hourly rate would compensate me for the additional effort in explaining something multiple times in various ways or creating samples which would otherwise be unusable.
Be certain to set clear expectations. If possible create a bullet list of you plan to train.. a syllabus basically. This will give the client something to reflect upon to see that there is a method to when any particular aspect may be the training subject. You can also explain each bullet a bit with things like "This part is going to feel like you aren't making a great deal of progress, but it's overall necessary for everything to come in the future."
