This is one of the challenges you have to complete in campaign mode. You need to get every single coin without getting any skull coins. It isn’t hard, but it might take you quite a few tries because you miss one, grab a skull coin, or run out of time, you'll need to start over.
The gold coins are the ones you need to collect, the silver coins are skulls. You need to take it slow in the beginning, for the first twenty coins or so because they’re spaced pretty far away from each other. Utilize your turning power () to make sure you hit every turn and get every coin. Where there’s a skull there’s probably a gold coin, so be aware when your going down the hill. You want to be careful, but also fast because you have a time limit. Get all the coins in time without any skull coins and you get the achievement.