Choose a Topic
First, choose the ring topic that interests you. Surf a few rings. Does the ring fragment itself appeal to you or is it boring and unimaginative? As that is the first thing that catches your eye, a well designed ring fragment will attract more visitors.
Some things to consider. The graphic. Does it show on every site visited? Is it pertinent to the ring? Navigation. Is it easy to find the ring home page? Does the ring have a home page or just a hub? Are the needed navigation links on the ring fragment?
Surf the Ring
If you are satisfied, go on to the next step. Surf the ring. Can you surf the ring without encountering broken links? If the ring is very large, that may take some time. Are the sites appropriate to the ring? One wouldn’t want to surf a ring with inappropriate content. For that matter, one wouldn’t want to surf a ring where you can’t access the content either cause a site is password protected or links to and from content pages can’t be found. And one needs to consider the annoyances too. Some sites are popup and or ad filled. Will that be an annoyance to you or can you deal with it? There are tools, browsers, ad killers that rid one of the annoyance but some come with a cost in that you can’t view the site content.
Check the Hub or List page
How many sites are in the ring vs how many are in the queue? Have they been in the queue long? Now large queues may mean automatic functioning of the ring as in member sites being moved cause of failure of code. There are ringmasters who keep a site in the queue until they can troubleshoot why the ring fragment can’t be found, ie. the wrong page is listed and can correct the problem. Some systems allow this. However, very important, is it updated frequently? If not, that may indicate a ringmaster who doesn’t maintain their ring or a ringmaster on vacation. Might want to watch that one before committing to a ring.
One criteria you may not know until joining is how accessible the ringmaster will be to aid you if you have problems. Some web hosts have problems with the different methods of adding the ring fragments, ie. html vs navbar. If the ringmaster is available to help you with your problems should you encounter them or points you to a resource that can help you, all the better.
These are the basics. If you find the ring satisfies these criteria, then by all means join!