Sometimes a second dwarf with appear on the track. Collect him, because he will be a second life if your current dwarf crashes or leaves the track.
Dwarves
Each dwarf has a helpful special ability.
Sleepy: Can sleepwalk and float through the air. Repeatedly tap to have him make a floating jump to get gems or avoid falling off the track.
Sneezy: Executes a sneeze to get a speed boost. Also can be used while in the air to avoid a bad jump.
Happy: Plays his cart piano to attract gems.
Gadgets
Try purchasing the following useful gadgets.
Landing Boost: Gives a speed boost if you stay in the air long enough.
Steam Engine: Gain a speed boost when travelling uphill.
Double Jump: Self-explanatory.
Jewel Stick: Attracts slightly out of reach gems.
Power-ups
You can also purchase one use power-ups, with "Double Gems" being the most useful.
Extra Life: Self-explanatory.
Double Gems: Gives double gems.
Gloom Repellent: Automatically destroys all enemies.
Chest Opener: Automatically opens chests.
Head Start: Boost at the start.
Speed
Accelerate until your your dwarf's mine cart has a white glow leaves a trail. While in this state, the following things will happen.
Enemies are automatically defeated when you crash into them.
Spike bumps are destroyed.
Chests are automatically opened without jumping on them.
To maintain your speed, jump over small bumps, avoid going uphill, and stay on downhill slopes as long as possible. You can also bounce off of chests and enemies to maintain your speed.