How to Train Your Dragon

You will unlock the Expert difficulty after completing the 4th tournament in Story mode.

A little tip for this achievement. You know the ring that counts as a checkpoint, right when you pass thru the ring look at the button combination and press pause. Then just prepare to hit that combo when you unpause, that way clearing 5 in a row is a breeze.

This achievement is essentially the same as the requirement for getting gold on this challenge anyways (5 points = 5 checkpoint rings), so it's pretty easy. The game will auto-steer pretty well with a couple exceptions that I've noticed: immediately after the first (and technically fourth) checkpoint ring you may want to steer a bit more to the right, and between the first and second fire rings after the second (and fifth) checkpoint ring. This second fire ring can be hard to see due to the brightness of the sky, so try and prepare for that when doing the novice and normal-level races.

Every fire ring uses A to boost, so don't worry about having to check the button on those. You can also tap A when not going through a ring to boost, just be sure not to fill the Fatigue bar or you won't be able to boost for a few seconds and your dragon will slow down. Therefore, the only memorization issue will be the checkpoint rings, which Spazpol is absolutely correct about. Press either the Xbox Guide or Start button to pause as soon as the combination appears, prepare your fingers, and unpause. You should have no problem with the time as long as you don't miss these combos or flat out fly past any rings.

This one is straight forward but you have to be very careful because each of the ring checkpoints is a two button combo. I hope this helps.