I would suggest playing the same templates repeatedly first, just to gain a basic understanding of picking, expansion, etc.. There's no point in learning a whole bunch of templates just to grab the basics of strategic gameplay. Stuff like Biomes of America with the layered bonuses, are a total mindf*ck if you are just getting into things. It's doable, but much, much harder than it needs to be.
So the most obvious way to accomplish this is through autogames and the 1v1 ladder. I'm not saying do everything this way, that gets boring. But start your learning focused on a single template. Once you got the basics down, you can always expand the principles to new templates. Also. If you really wanna make the best decisions possible, yes play multiday. But that's way too slow for practicing the basics. RT games are where its at. 5 Minutes is enough time to think turns through, unless you are hard-core analyzing your opponent's many possible expansion routes over a number of turns.
There's a bunch of guides out there too, that you could look at. This is a decent collection. https://www.warzone.com/Forum/168132-strat-guides
On a side note. Don't push the clan to adapt too quickly, it works better to encourage participation in strategic events, preferably of the more casual variety. I would say avoid events where you will be frequently paired with people from Masters/Lynx/insert other eliteish clans. You can definitely learn some stuff from those games, just by seeing what they do, but they are not appropriate competition for your clan, most likely.
The problem is that it's no fun to be repeatedly curbstomped by people who are almost literally playing in their sleep. So look for competition at a similar level first. You improve the fastest by being constantly pushed to take little steps. It's an easier adjustment, and vastly more sustainable.
edit: I'm no great shakes, with a couple of respectable ladder finishes. If I wasn't borderline inactive due to interests and RL, I would have tried helping you out, since you show actual initiative. Best of luck!
edit 2: I know in the past it was possible to invite high skill players to play games with you, and talk over a few bits of the game each time. I'm not sure if this is the case still, but it's worth pursuing with a little buttering up. Most people are happy to play towards a mostly free win, if they have the time.... ;)
Edited 12/5/2019 08:11:38