As the Red Coin star of this course, you will find that it’s not very hard to get them all, as they are relatively close to one another and not spread out like other courses. In fact, the Red Coins in Tall, Tall Mountain are in two groups, although there is a fear of losing a life because of missing a jump for the first part. When you begin, follow the mountain trail until you get to a bunch of mushrooms, as that is where the first four Red Coins will be located. You will need to be extra careful with your jumps here, as if you fall, then you will lose a life.
After collecting those four coins on the mushrooms, continue along the mountain trail until you reach the Monty Moles. There are multiple platforms along the wall and the remaining four Red Coins will be found along them. Jump on the first ledge you see, then to the next one, where two Red Coins should be within view. Collect those, then keep going upwards until you reach a second set of Monty Moles. There will be another Red Coin that might be partially obscured by the ivy climb thing. The final Red Coin is found at the very top of this little section. The star will spawn on the big mushroom found right next to the Monty Moles at the bottom; a simple Long Jump is enough to reach it.