I've been the head of a few clans in my time and after reading Prometheis2000's article, I decided to write my top tips (If they are the same as Prom's then that just makes them even more important!)
attack your own company unless if you are attacked first or if you are at war.
2: Always try your hardest to avoid wars with clans in your company.
3: Make sure you don't (If you are planning on) give credits to new members unless if they stay for a certain period (A week or two is best but in serious cases, 30 days might do).
4: Try not to accept outlaws as they ruin your clans' reputation.
5: Help other players to get on their good side.
6: Get as many alliances as possible.
7: Give the right people the right roles and praise everyone for good work but do not scold them in an agressive way if they do anything bad.
8: If you see people leaving your clan, use the appropriate mediums to try to get them back. These include (but are not limited to) Clan Search, Whispering them, Lowering minimum levels, Going on hunts with possible members, Promising that they will become FE with your help and also non-DO methods such as Teamspeak, Skype or even Facebook and Twitter.
9: Be on at least once a day (Leader/Co-Leaders) and at least once or twice a week (Members).
10: Kick members if necessary.
11: Leaders, try
to make sure you don't get chatbans!
12: Set up a good community in this Sub-forum.
13: Write a proper clan description.
Now a few tips that might help the members stay even more!
1: Put the tax low or high depending on how much Clan Pay you are willing to give.
2: Why not try a Clan lottery? Everyone picks a few numbers and if they are the ones that you wrote then they win a prize! (1-0 Creds, 2-1,500 Creds, 3-5,000 Creds, 4-20,000 Creds, 5-100,000 Creds, 6-Jackpot)
If you have any more ideas or think some aren't that useful or have been repeated in this thread then tell me!
Apart from that, have a Good day, Rookie Leaders and all!