Navigation is great, but there is more to it than just looking at the stars. Exploring the galaxy of Mass Effect to mine its planets is a requirement for those who wish to aggressively explore research. The minerals Shepard picks up on foot won't cover much resarch at all.
Mining the resources of planets involves orbiting, then entering the scanning view. To scan, hold right mouse button and pay attention to the readings displayed on the right, as well as the accompanying sounds. When the white line spikes over one or more of the resources, and the pace of the clicking sound speeds up, a probe can be sent out to retrieve the resources (left mouse button).
Different planets will have different levels of resources and different kinds of resources. The amount of resources likely to be found is indicated when first viewing a planet, just above the planet's description. It can be Poor, Moderate, Good, or Rich. Generally, only Good or Rich planets are going to be worth your time. Note that a planet's resource rating will diminish the more heavily you mine it with probes. Once you've whittled a Rich planet down past Poor status all the way to Depleted you know you've made off with just about all the goods.
The flavor text in the planet's description might also give an indication of the resources to be found on the planet. Sometimes one resource will be described as being more plentiful than others, so if you're looking for a specific resource pay attention to the flavor text.