There are several types of blockers that will impede your matches, such as the short lines on the squares that will prevent you from making matches or piles of dirt that are placed as obstacles. Attempt to remove them as soon as possible to increase your chances of filling the board with elements you can match.
Drones
Drones are special items that appear when you create long matches, such as ones that explode vertically or horizontally. Drones can be moved on the board if they are not at the end of a line that you match. Take drones to where they will cause the most destruction or most use. Use them to reach elements that are hard to get to. Drones can be improved with the iridium you receive. Try to keep their improvements evened, as they will all be needed eventually.
Matches
Try to create long matches to earn higher bonuses for those elements. It is possible to get up to 100%. This becomes useful when you must destroy asteroids or collect a specific number of elements. Ignore a particular element for a few matches to let that type of element to fill the board. This will in turn make it easier for you to create a very long match, which in turn will increase your bonus. Consider matching one or two types of elements to allow the board to be filled with what is needed.