Yeah I like geocaching. Here's some of the wisdom I've picked up after my first year.
GSAK
Geocaching Swiss Army Knife. Great software, though a bit non-intuitive for a novice user. powerful. If you figure out how to work this well, it can make paperless caching a breeze. It can create the palm-formatted file that Cachemate uses as your database.
Cachemate
Software for your PDA. A database, basically. You can use this to go paperless (meaning that you don't have to print out the cache detail pages). You upload the file GSAK made for you (coordinates, hints, terrain/difficulty ratings, past logs, etc) and you log your finds via your PDA. This was a godsend one time we were away from home on vacation and my wife's laboriously printed papers all flew out the car window!
Not too expensive, maybe $15? I think this integrates nicely if your PDA has a GPS built-in, but it is also very handy even if you use a separate GPS receiver (like we do).
We were headed to Gatlinburg, TN one time and I just quickly downloaded all the caches (using a pocket query on geocaching.com) within a certain radius of that area. We could see if we were near one, and then had the details of the hunt instantly available on the PDA.
Travel Bugs
These are little items that move from cache to cache. Sometimes it's a little Gnome figurine, or a carved piece of wood. Anything will do. It will have a dog tag attached to it with the Travel Bug tracking number. You put that tracking number into Geocaching.com site and you can see where it's been. Some travel bugs go worldwide! You can ask that folks take pictures of them near fun stuff, or you can give them goals (e.g. To travel and have it's pic taken in front of Waffle Houses).
You don't even have to have a GPS to buy a travel bug dog tag from geocaching.com (and attach it to whatever you want) and you can watch it travel. You would have to find a friend who can put it in a cache for you, though. Or if you logged onto the site, you could post in the forums for someone in your area to contact you. Most cachers would be happy to help.
I once saw a travel bug that was a school project for a class of 5th graders. They were learning about geography as their bug moved from place to place.
You don't need no GPS
Well, not necessarily... There are some fun things you can do with geocaching and the web site that don't require a GPS unit. I've mentioned Travel Bugs.
Another thing is that you can hide your own cache. Join geocaching.com and read about the rules for placing/hiding a cache (like it can't be near a school, in a state park, etc), and then find a place fairly close to you (so that you can keep the cache maintained). Get another geocacher with a GPS (like maybe from the forums) to mark your hiding spot and give you the coordinates. That's all you need to submit the cache to the web site to have it go active.
Then you, or your family, can keep an eye on the cache and read (via the cache's log book) about all the adventures folks have trying to find it. You can also monitor the contents and log any travel bugs that stop by your cache, and see what neat stuff people leave for trade.
If you couldn't find a willing geocacher to nail down the coords for you initially, maybe you could use Google Maps to get close enough for the first few cachers to find it (maybe you give them extra hints or something).
Free Login at Geocaching.com
It doesn't cost anything to join the site. That will give you access to the forums, where you can ask all kinds of questions about what GPS to buy, or what caching is all about. You can also search your area to see if you've got any near you.
My home town has maybe 6 total, while the are I'm in now has hundreds.
Google Earth
GE has a .kml file you can download that will give you a layer while using GE that will show you any caches in the area. I think only 100 "views/refreshes" a day, so don't wait till the last minute to plan a trip with that. What I do is copy them to "My Places" from the Geocaching layer, then I am not limited at all.
Family
Most cache detail pages will tell you if a cache is good for bringing kids along. It can be a very fun and educational experience for everyone.
Right Under Your Nose
There are many urban caches. Containers designed to fit into the environment unnoticed. If you live in a reasonably-sized city, you probably pass several on a regular basis.
Some of these contain only a tiny slip of paper (the log), so they can be as big as a small marble. My wife even bought a few containers off ebay that were old golf balls with holes drilled in them to put the containers in!
Terrain/Difficulty Ratings
Don't worry. Each cache has a difficulty and terrain rating. So you can start off with the easy ones. Or just stick to those that your weary old bones can handle. ;-)
Handicapped Accessible
Many caches are handicapped accessible, so taking aged grandma -- or your son who broke his leg and is aching to get outside -- can be fun for everyone. You can limit your cache searching to only return those kinds of caches.
Park & Grabs vs. Hikes
There are all kinds of ways to get to caches. Many are Park & Grabs, where you basically pull up to (or near) an object, and it only takes a few minutes to find the cache, and you're on your way.
However, some are more for the naturalist, where you have a 2 mile hike (found a fabulous waterfall in the Blue Ridge mountains this way) to get to the cache site. The cache detail page should let you know all this and more. Sometimes they even give you suggested parking coordinates.
Don't Trust the Arrow
With my eTrex Legend GPS, there are two views that can be used when hunting.
1) Map view - You see yourself on a map, and you see where you've been, and you can see your cache waypoint as well.
2) The Arrow - There's another view with pretty much an arrow that points to the waypoint location and it also tells you the distance.
I always use the map view, while my wife enjoys the simplicity of the arrow. However, when you get within 30 ft. or so, you gotta switch to map view, if you haven't already. The arrow is not meant to be used in close proximity to what you're looking for. It will send you in all kinds of wrong directions.
The arrow will also screw with you if you're in an area that has a weak signal. In map view, you can watch if your present location indicator stops moving, indicating that it's lost you. You can then still have a good bearing until it kicks back in.
With the map view, you can see the cache in relation to your movement. "oo, I just passed it to my left" etc.
It's a Hunt
On my first cache I did two things wrong. 1) I relied on the arrow, and 2) I expected the unit to put me right on top of the cache. I'd follow it, bend over and pick it up. WRONG. It's really about the hunt. That's why it's still fun if only one of you has the GPS, and the others are hunters. GPS guy, make sure you communicate with your hunting party so the are in on the action as much as possible! I say things like, "100 ft straight ahead", or "we've got 300 ft to go", or "looks like maybe near that big tree over there."
At best, the unit will only put you within 9 feet of the cache, and with some caches hidden well, that can seem like a mile. However, if the person who hid the cache did not take time to get accurate coordinates, you'll find that you're 18 to 60 feet away from the cache.
You use your GPS to get you as near as it can, and then it's all about the hunt.
Get that Signal
Your GPS must have a line of sight to the sky (specifically at least three satellites) to work. I learned this the hard way. The signal will penetrate glass, though. So your dashboard is a great spot as you're driving.
Trees usually don't pose too much of a problem unless they are really dense.
If you're in a low-lying area, it can be tough to get a signal.
You can get false readings near tall buildings as the signals bounce around before they get to you.
If you're in an area where reception is sparse, weak batteries can turn a weak signal into no signal.
In a wooded area, I find that keeping moving helps the GPS to keep a better fix on me than if I stand in one spot.
Batteries
One or two days of Geocaching will eat up two AAs in my Garmin eTrex Legend (not color LCD). I recommend getting some rechargeables. And always bring spares.
Read the Logs
Read the latest cache logs (on each cache's detail page) before you head out. It may alert you that the last 4 people who've tried to find it have not had any luck (indicating that it might have been stolen). Or maybe they'll mention that the coords are wrong. Usually, everything will be fine, but these are details that can prevent frustration in the field.