Rocket League

You unlock a new item after every match you finish so this will come with naturally playing the game however if you just want to get this achievement over with or want to unlock a lot of customization items for yourself the quickest way to unlock items (from what I have seen/done so far) is as follows:

- Go to Exhibition
- Arena = DFH Stadium (any arena will do though)
- Team Size = 1v1
- Bot Difficulty = No Bots
- Go into Mutator Settings and change "Max Score" to 1 Goal
- Create Match
- Choose either team
- Just hold your boost right off the start going directly at the ball, just as you are about to hit the ball brake (milliseconds before, this is just to prevent the ball hitting the crossbar instead of going in)
- Skip the highlight, hit ok or equip on the item you unlocked then hit ready to rematch the bot

With this method each match only takes 20 seconds or so (including loading) so it would only take about 15 or so minutes going from exactly 0 but you most likely saved this for later and already have a lot of items unlocked so it won't even take that long. Enjoy!

As specified by A Batwoman in the comments of another guide, items are now attained through challenges.

Challenges are accessible via when in the main menu. Once you have completed a challenge you need to go and manually claim it. Unsurprisingly, these are claimed by selecting the Claim button.

Strangely, the challenges interface is a little weird and even is a bit glitchy. Sometimes in some menus you can't select individual challenges. If that happens then back out one level and go in again. Also note, on the first page you need to go down to the challenges using .