The following opinion may be blasphemous but I'll say it anyway: I don't think there is anything particularly 'mysterious' about weaving. There are a zillion ways to thread the loom and make patterns, but the basic things are all the same.
To weave, you need to know these things:
- how to get your warp ready and beamed on with even tension (and there are actually several ways to do this, so you should try them all and see what works best for you and your equipment)
- how to thread your heddles and sley the reed (which is different for various types of looms, but essentially consists of poking a thread through a hole, sometimes with the aid of a little hook device, keeping track of where you are in the sequence as you go)
- how to do tie ups (if you have treadles) (which means connecting two things together with a loop of string and/or clips of some kind)
- how to properly toss the shuttle / manage selvedges (keep the edges snug but allow extra thread on the weft toss so your edges don’t draw in too tightly, and do it evenly)
- how to hemstitch (this keeps your fabric from unravelling, and there are several ways to do it – the one I like best is basically a loop around a group of warp threads followed by a blanket stitch into the woven fabric)
- how to wet finish your fabric (because it ain't finished till it's wet finished: this means washing and possibly steaming or otherwise abusing your finished fabric so it ‘sets’, the specific technique varies with the fibres involved)
The rest is details and practice.
The equivalent for spinning would be to say you have to know how to prepare and select fibre, how to draft, how to insert twist with whatever equipment you have, and how to ply. I mean, yes, there's a lot of fine detail that isn't covered in that short list, but if you know how to do those basic things all the rest comes with practice and looking at what you are doing and saying to yourself "how could I do this more efficiently/effectively?"
For weaving, looking at different pattern drafts and skimming books about weaving is really interesting to me - like looking at knitting patterns and seeing different ways of constructing objects with sticks and string, or watching other spinners work with spindles and wheels and picking up little tricks from how they hold their hands or whatever. You figure things out as you do them: you realize “oh, if I thread the edges in basketweave, I don’t have to worry about the twill not catching on every pass” or “this fabric will collapse a lot as soon as I take it off the loom, so I need to be gentle with the beater so I don’t squash it too much now, it’ll snug up later on in the process”. Or, a really cool thing I learned from a library book recently, “If I skip a bunch of slots in the reed then do a bunch side by side, I get fabric with vertical stripes of solid fabric interspersed with more open sections”. (I want to make curtains like that.)
But, really, it's just not as hard as it looks. The basic steps are the same, whether you are working with 2 shafts or 12 - it's not that you thread heddles and tie up treadles differently, you just have more of them. Yes, designing your own patterns gets more complicated with more options but there are so many references out there, why wouldn't you start off by following what others have worked out, see how it works, and then go off on your own? That's how I learn, anyway.
And now, I’m off to wind a bunch of bobbins. Gotta start on a coat!