It is not a good idea to just leave a clan and join another one. That is called clan-hopping. Official clans normally look at your history, and clan-hopping counts against you during a voting process.
You should try to get your current clan more active (if you are in one, in which you currently are not at the time I write this post). If that is not possible, then request/notify that you are leaving due to consistent inactivity despite efforts. Therefore, if a clan decides to search up your previous clans, they might understand it more.
maxfire1, post amount doesn't always count. For example, if your posts are of high quality but you have a lower amount overall, the amount of information, it's usefulness, and overall reliability will count. If you believe that your posts match that criteria, you can ask the clan to view your posts instead of your post count. A wide-forum wibbler will have thousands of posts in a week or two, but most clans don't want an insane wibbler, now do they?
Look around a clan before you pick. Check it's activity. If there is more than 3 hours of delay between each and every single post, you might want to question that choice. If the average delay between posts = 1-4 days, that clan is very inactive and should be eliminated from your choices.