Good meters use 'O'-rings to seal the case and jacks.
In some meters, the probes can be attached to the base of the holster, allowing easy one-hand probing of circuits. Other designs of multimeter even incorporate one of the probes into the body of the meter itself, making one-handed operation very easy. The probes and leads are very important. Both sharp probes and also alligator clips should be able to be used, with the better meters having screw-on alligator clips which attach over the probes. The leads themselves should be heavily insulated, and should feel thick and durable.