From what I have read and seen online there are a few ways to make it easier to get this achievement.
1. Play 1v1 exhibition with no bots and with single goal win - keep playing until no more items pop up (these are the basic items) > this means that only painted items etc will come from online matches (if any)
2. Before starting, pick a new antenna.
Certified and painted items will be awarded only in the first 10 hours of playtime every week (antennas track the total time played)
Credit goes to: crsN9un5 on YouTube for this information. Link: