There is no guide for this game yet. But apparently it is EASY POINTS! 

Roadrunner - 40 points

Lead a race from start to finish (Not achievable in splitscreen).

Bully - 30 points

Take down one opponent (Not achievable in splitscreen).

Berzerk - 50 points

Take down three opponents in a row without crashing (Not achievable in splitscreen)

Rampage - 70 points

Take down four opponents in a row without crashing (Not achievable in splitscreen)

Acrobat - 40 points

Perform a two stunt combo (Not achievable in splitscreen).

Wire Fu - 60 points

Perform a three stunt combo (Not achievable in splitscreen).

Adrenaline Junkie - 40 points

Stay in adrenaline mode for 30 seconds (Not achievable in splitscreen).

Boostaholic - 60 points

Stay in adrenaline mode for 60 seconds (Not achievable in splitscreen).

Hoarder - 30 points

Unlock half of all unlockables in career mode.

Pack Rat - 50 points

Unlock all unlockables in career mode.

Stingy - 30 points

Collect $50000 in career mode without spending them.

Hangtime - 25 points

Hold a stunt for 2 seconds (Not achievable in splitscreen).

Frozen - 50 points

Hold a stunt for 4 seconds (Not achievable in splitscreen).

Big Air - 25 points

Stay airborne for 3 seconds (Not achievable in splitscreen).

Orbit - 50 points

Stay airborne for 5 seconds (Not achievable in splitscreen).

Untouchable - 60 points

Win a career race with your sled intact (Not achievable in splitscreen).

Backflip - 25 points

Perform a backflip (Not achievable in splitscreen).

Double Backflip - 50 points

Perform a double backflip (Not achievable in splitscreen).

Frontflip - 25 points

Perform a frontflip (Not achievable in splitscreen).

Double Frontflip - 50 points

Perform a double frontflip (Not achievable in splitscreen).

HeadSplat - 60 points

Land on top of another player (Not achievable in splitscreen).

Crowdsurfing - 40 points

Collide with the spectators (Not achievable in splitscreen).

Secret Achievements

Woodcutter - 40 points

Collide with 3 trees in a race. (Not achievable in splitscreen)