Jim Divitale, Photoshop guru extrordinare also told a bunch of us at the PPOC convention in Winnipeg to start your panorama series with a shot of your feet, and when you're finished, take another shot of your feet. This way your series is "bookended" by your feet and you'll know which images belong to which series.
This is by far the best info I have been given about panorama photography! Seriously. When you're out in the field, shooting panos all day, once you get back to you computer, you will have no recollection of where one set starts and the other ends. the feet shots save you a ton of time, and frustration.

Let's assume here, you are not using your tripod. Here is the set up and process:
Visualize the scene around you and imagine that you are in the centre of the green spot. The green is ground, foreground and floor. The brown is the elevation zone, in which you should have objects that extend onto the sky (blue). These may be trees, mountains, buildings, poles, generally they will have a vertical quality. The blue area is the sky and for interest, it's best to have some clouds, as a pure blue sky is unimaginative and hard to blend in the stitching software - from the dark side to the sunny side.
On a flat plane this is what your plan should look like:

Notice that the spatial zones each take up 1/3 of your panorama image. Some of the vertical elements can extend behond the 1/3 area but if there are too many, or if there is not enough sky, the tiny planet won't look like it's floating in space. If there are too few elevations, your final panoramic planet image will look....guess?...yep, flat. Flat is not exciting or invigorating - height, terrain, texture are all great panoramic photo elements.
These are good rules of thumb even if you are only making a normal panorama photo - the rule of thirds is pretty universal. Break it only if you know what you are doing.
This article was printed with permission from Alexandra Morrison, who is a professional nature photographer, digital artist and publisher of the Nature-Photography-Central web site.