Neodymium magnets are very strong, but also very brittle. When a magnet is attracted by another magnet or metal, it might fly itself resulting in a harsh collision. The magnet might break, but even more dangerously are the fragments that fly around. A splinter might hurt you (fly into your eye), so be prepared wear safety glasses.
Attaching Neodymium magnets permanently to objects is sometimes hard. I tried to solder them, but that’s not easy and heating the magnet will lessen it’s strength. Gluing is easier, and can be applied to any surface. Use a strong glue (geltype), clean the magnet before applying. You might even sand the surface of the magnet a bit, to get a rough surface to which the glue can stick. In my experience hotglue is not strong enough to hold the magnet in it’s place.
Conductivity
Luckily the magnets conduct electricity, so that gives you options for making and / or breaking a circuit. Especially together with copper tape you can make nice circuits.
Metal washer
Another way of fixing magnets is attaching a metal washer with glue to a surface. You can then stick the magnet on the ring, and eventually reuse the magnet for other projects.
Stuck together
Sometimes it’s hard to pull a neodymium from another, try to slide it off.
See this Wikipedia page on Neodymium, for more information on this rare-earth metal.