Thank you for your replies. I'm not here to debate whether Second Life is a game or not, that is matter of personal interpretation and perspective.
I managed to find my way to Caledon Oxbridge Gateway, so I'll see how that goes.
UPDATE: So, I followed the Caledon Oxbridge path and learnt a couple new ticks, it's better than the SL tutorial but still doesn't cover things that seem important.
Something I've noticed is most, if not all, of the popular 'quality' creators have in-world stores where they sell their content, rather than through the online marketplace. From YouTube videos I've derived that meshes, textures/skins, heads, and other elements are not universally compatible. I've visited about a dozen, and they tend to be poorly set out and don't clearly explain (a) what something is and (b) compatibility with other body parts/meshes/etc.
Is there a way to find this out easily? Feels like you either know or you don't, and if you don't, you're screwed.