1. Stick to the theme. If you make a difficult to find cache, make every waypoint difficult to find. In all other situations, make sure the waypoints can easily be found and questions can be quickly answered so the cacher can focus on the theme (eg. navigating or hiking). Also hide your waypoints in the same style, this makes them easier to find. Good. Bad.
2. Don't use wordvalues. Because they do not make sense and take ages to calculate. Simply ask for the lettervalue of the 3th and 5th character. Bad.
3. Make your cache easy to find. Geocaching is all about finding a cache (and not about searching a cache). The cache should be hidden for mugglers but not for geocachers. Good. Bad.
4. Cache size to small. If I have survived the challenge of your cache I want a decent log book to write down my experiences. Not a piece of paper asking for a name and a date. Good. Bad.
5. Take criticism serious. If a remark about your cache keeps coming back in several logs, change the situation. Bad.
6. In a forest 'behind a tree' is never a good hint. Neither is 'see spoiler picture'. Always add a good hint. If I think a cache has been ripped, I want to be sure I have looked at the right spot. Bad.
7. Perform maintenance if geocachers write a 'need maintenance' log.
8. If a special tool is needed, mention it on the cache page. Also use attributes, especially the wheelchair icon. Good. Bad.
9. Give an estimation of the amount of kilometers or the time needed to find the cache. Good. Bad.
10. Think about what your cache adds to the already existing caches in your neighbourhood. If you can not come up with an answer within 2 minutes, archive your cache.