It's the line of work I do, i fix mobile, computers, laptops, tablets etc etc. To me it isn't one job, but a series of jobs.
They always go great, I have tons of experience in doing these types of repairs, so to me the right tool is more important than any guide. The tools ifixit sells are amazing quality.
Just keep at it, i've been doing it for a little over two years now, at first it's intimidating because how so small the components in most mobile/computer/tablets can be, but after about 20 of them. It starts to feel natural.
Never rush anything, if it fights you look for a screw, if you can't find any; use a soft prying tool or a heat gun to loosen the glue.
In my experience so far, most things are held together with screws (various types), from hex, to torq, pentalobe, triwing glue and of course clips. Patience is the key to taking apart anything.
If it doesn't feel 'right' coming apart, never force it. That's how you break things, especially in cases like the HTC One (held together by force and clips).
Worse case scenario there's hundreds of guides on sites like this to help you dismantle or repair devices. Of course if you just follow things through and are thorough and careful, you can take apart anything without a guide necessary : )