I need some help, haha - just got the start of DLC3 and I've farmed up a bunch of relic gear but I'm having trouble piecing it together.

I've been looking at some builds on YouTube but, frankly, they mostly use perfect gear and they assume a lot of existing knowledge, or they're old videos from when the DLC wasn't out yet.

Is there anywhere that lists or talks about common affinities and WHY they work in combination? I had a look at the big spreadsheet that's linked here quite often, and it is useful but again, assumes a lot of knowledge. It copies and pastes the affinity descriptions from in-game which don't often say exactly what something does ("enhances the 120% affinity" for example. Like, by how much? An extra 100 strength, or 2 strength?), so trying to pick affinities to aim for relies on me already knowing what they do and how strong they are.