Tbh lower tier clans like vanguard, df2, jaja, dk or vr would probs be very pleased to get more members. How ever df2 still has very strict way of accepting people to the clan even tho theyre not top tier competitors anymore. What i recommend is to just make an acc on some clans forums, post and intro, join their discord and get to know people. Last step is what everyone in the clan would tell you to do if you introed. The reason for that is because nowadays every new random member(atleast in the main clans) is expected to be a spy for some other clan and you will get declined. So for that reason you need to get to know people first. In some clans introing means that youre actually trying to get in to the clan at that very moment and thats why they might decline you but for example in Cutthroat introing just means that you're saying hello to all the people in the community and get to know people.
Of all those clans i just mentioned above i would say Vanguard or VR would be the best ones for you. Decent community, some experienced members, not the best quality but definitely good places to learn more. Vanguard is more of a community and people in VNG PvM alot too if youre into that type of stuff but VR is more active in PvP and has better quality.