The first thing that comes to mind is how you plan to get visitors. For example, when I see the Gmail login tutorial, I can not imagine that someone would search on Google how to log into their Gmail account (even if someone did, the likelihood of your website showing up in the results of Gmail). search before Google official help is something like 0.000 … 1%).
Frankly, I would consider another topic for your tutorials. Even if you receive visitors, is there any reason to reread something about Gmail? Most users simply log in and see how things work (the interface is easy enough to use). I would recommend writing about something that can not be learned too fast, so there is the possibility of getting repeated visits to your website.
Anyway, good luck!