Hey lagant. I'll give you my take on how to be a good clan leader.
Golden rule: Perseverance
You decide when your clan dies, not the lack of members, not the inactivity, the leader is the fundamental piece of a clan. If someone is inactive look for someone else, worry about your clanmates if you don't see them for a week send them a message asking if they're ok or if they need something, show interest in your clan, and make your clanmates to be interested in he clan by gi ing them important tasks or just making them feel important in the clan.
My clan NEMESIS has been alive since 2010, there was a time where it was just me and kiryu (my co-leader), it was 5-6 months of a 2 members clan, I was about to give up, but there was something I was doing wrong, I was waiting for members, instead of go out and look for them. That's how I found the current members I have and don't be afraid of kicking an inactive person, first you gotta find out if he is inactive because he is lazy or because of real life issues, they all have life too, and you gotta decide to kick them or not.
Always show fresh content, show the world the kind of cool stuff you can do, even if is just a 3 seconds collab, is still something you all made toghether, those kind of thing makes your bonds stronger as clan members.
Always keep in contact with your clan members, ask them about their lives, show interest as I said above.
Your co-leader is an important part too, they are there fro some reason, chose someone loyal, someone who will stand by your side no matter what. He/she will and must help you to make decisions and help you to organize everything, you feel better when you know there is someone whiling to help in emergency situations.
Going back to the golden rule, it is up to you if your clan is a shitty inactive one, or a clan that is capable to make the difference and show everyone what are they made of.According to my opinion, and considering what I said above, if a clan dies, is the clan's leader fault.
I hope this helps.