A few things I wish I'd known sooner:

• Uncommon elements are grouped with the common ones on the "Show Resources" overlay on the system map. For example, if you were looking for platinum on Bondar, you'd head to one of the areas with lead because that's the common element that is grouped with it (along with tungsten). It's not always clear what's grouped with what on the planet overlay, but when you're on the surface and have a resource in front of the scanner, you can hit "Show Resources" there and it'll show the groupings. The Scanning skill in the Science tree will give you a better breakdown.
• When you're on the surface tracking down planet traits, you can hit Scan on distant "Unknown" markers to get a slightly more specific identifier and icon. That way you don't have to waste time hiking 1km to an artificial structure or a duplicate planetary trait.
• You can double-click a part in the ship builder to select all connected parts (don't know the gamepad button). Good for complex builds or if you want to repaint.