Tripods like the 190XPROB often come without a head so you can choose one that fits your needs.

For compatibility, the key point is the tripod’s 3/8-inch mount; choose a ball head with the matching base mount or appropriate compatibility. Your Panasonic G3 is a relatively small, light camera, so you likely do not need a large heavy-duty head.

The main thing to check is load capacity: add the weight of your camera and heaviest lens, then choose a head rated for at least about twice that. That gives a safety margin and usually improves stability.

Also consider how the camera attaches:

• direct attachment, or
• a quick-release plate system

A quick-release plate is usually more convenient. For a small camera, a smaller plate is often a good fit.

Feature-wise, not all ball heads are the same. An independent pan control can be useful, especially for panoramas and sometimes video. In general, spending more can get you a head that supports more weight or offers better controls, but for a basic lightweight setup you do not necessarily need an expensive model.