Why don't you try finishing up the tutorial? You might've mastered the first step, but nailing down the fundamentals is what's important.

Unlock all trophies

Beat the Labyrinth without dying or failing

Collect all of the Minotaur Horns

Perform a 1000-hit combo

Win any event with a tuned car

Use your Rocket Boost for a total of 5 minutes

Play an Exhibition match

Complete a match in all multiplayer modes.

Reach level 10 in multiplayer.

Kill a zip-lining enemy player in multiplayer.

Kill 2 multiplayer enemies with a single explosive.

Complete a match on Hometown with at least 5 downs or executions