If your focus is on groups that can help you learn more strategic play, then there are a number of viable candidates.
I would never suggest joining a clan that does not have some players with high rankings on the ladders (most ranked 1-100 on 1v1 ladder can give you a fair amount of useful advice, starting out), or that have a lot of members. If they lack the former then you can't be sure that you will get very good advice, period. If they have a lot of members, then you should think carefully before you join, maybe ask around to see what people genuinely think of them, and be biased to listen to better players. They tend to be more mature and knowledgable. Likewise, clans with only a few members, are usually a tad unreliable, even if active.
Anyone who recommends/mentions a single clan, well, I would be wary of them. They may not know that much about other clans at all, or might not have the same interests to say the least.
You can see the full list of clans here:https://www.warlight.net/Clans/List
(going from the top for the most part - My focus is on clans that can teach strategically, since that seems more important to you if you build a network of friends you can still have decent roleplay games. I am skipping anyone who is not to my knowledge a clan that would be good for teaching newer players. This includes skipping trolls, elites, non-standouts, and other clans that AFAIK are not organized for a purpose you would be looking for)
Edit: Corp has been quietly working on improving their strategical focus despite their reputation. As a clan they are not top tier yet but it appears many lesser knowns are gunning for the top. Definitely worth a shot.
M'Hunters would be not bad though I think they have a minimum skill level required. The guide they linked at the top of their page is pretty helpful though :3
Hydra is also pretty decent for teaching newer players. In Hydra you do need to be a bit proactive about learning - usually if you want to learn from somebody you make a game with them. I'm somewhat obligated to toot our horn here given my membership but there are alternatives for sure.
One! has some good players, I don't know all of them, so they might or might not be open to teaching newbies. You would need to ask.
101st is also a teaching clan afaik. I don't know much about their inner works but from what I'e heard they are linked to the elite clan Lynx.
ACME Co is also a teaching clan from the looks of their clan page. ACL Tears is a good player for certain, I don't know very many others though.
[BR Fudew] is another teaching clan. I don't know of any elites in the clan but they seem reasonably friendly.
New World Order same as above but not Brazilian. :p
AOE ^ same as above but more RP focused afaik.
In my honest opinion, Hydra and M'Hunters are your best shots for teaching strategical play though you might need to practice a bit first before applying for the latter.
Now, you don't HAVE to go to a clan to learn from other players but it helps a lot. Try to read some early bit of https://docs.google.com/document/d/1NyhCpIQKShAbWGXicO_ph9whV_UyMS-3a7_re0C7R8Y/edit#heading=h.g1s8mzy7wor0
or GG's strategy guide as well - https://www.warlight.net/Forum/34678-gg-warlight-strategy-guide
Once you have an idea of what you are doing with the basics, and are getting a decent win rate on auto games, I've heard that some higher ranked ladder players are willing to play games with others and teach them a little afterwards. (You seem to be a nice guy, I might be able to help you out a little too)