The easiest way to get this achievement is by using pointman.
Put simply, what you have to do is
1. Maintain a chain bonus of around 3x or higher
2. Scoop up a red paint.
3. Fill up your grid with blocks right before the 4x power block.
4. Use your red paint right before hitting the power block, meaning you hit it with a full grid of red blocks.
This graph is an example of a good track to use for the achievement
1. The 4x power block is towards the end of the song, where you'll have the highest multiplier.
2. There's a red paint right before it.
After you make a match, you can see your chain bonus in the top right of the screen under your score. In order to get a 3x chain multiplier, you have to constantly keep making matches. They don't have to be big matches, so long as they're being made. (In fact, it's actually faster to boost your multiplier if you keep making small ones. It depends how you do it.) Note: you don't have to finish the match to keep your multiplier, just have one ready to finish. If you spend too much time without a match on your grid, you'll lose the chain multiplier.