Levels
The game has 5 levels, with each one being more difficult than the last - besides the secret level, and the secret area, as they do not follow this rule.
Level 1
This is level provides your first impressions of the game. It is set in the day, and tries to make the player believe that the game is going to be easy.
Level 1 is actually the most varied level, as it is a sort of mix of all the others. It teaches you the basic mechanics, and isn't particularly difficult in any way.
Level 2
This is the game's second level. Set in a darker cave environment, it completely goes against everything from the first level, and quickly sets a new bar for the game's difficulty.
Level 2 is actually where most players have stopped in the past, because it is usually quite frustrating to complete for the first time, since the game will trick you by anticipating where you will be in a moment, and then have an enemy or obstacle suddenly appear there to stop you.
Level 3
This is the third level of the game. It is set during Dusk, and instead of being on solid ground, for most of the level you are jumping between clouds.
This level is unique, as it gives the player two clear paths which they can take to complete the level, with one being much more difficult, though with a reward at the end, and the main path which the player is expected to take, which is significantly easier and just takes you straight on to the next.
Level 4
This is the final level of the game. Set at night, the player is to ascend a mountain, then jump between clouds to reach the end of the game; the Moon.
This is the most difficult section of the game for most players, as it throws every single enemy and obstacle in the game at you several times, and barrages the player with flying enemies throughout the entire cloud section - rewarding the player once they touch the flag pole.
Secret Level
This is the game's secret level. It is the player's reward for completing the more difficult path on the upper section of Level 3 - it is the only level of the game entirely set in the upper stratosphere.
This is the easiest level of the game, having no obstacles whatsoever. It is also the only level where the Regression Portal functions as a Progression Portal.
Secret Area
This is the hardest section of the game. Found by using a glitch in the game's engine and jumping up the hole in the roof of the first section of Level 2, it requires excessive use of the spacebar to pass through and a single misinput will lose you all of your progress.
This is the most difficult area in the entire game, period. This is because it requires you to spam the spacebar, alongside the A+D keys at exactly the right times - however at the end it allows you to either go to the next level, or even skip to the final level, passing through the secret level in between - so even though it is the most difficult place in the game to pass, it has the largest reward for completion.
Story
In Practise makes Perfect, you play as John - a regular man, who was going about his regular day coming to his regular home from his regular job, when suddenly, a portal ripped open in front of him, pulling him inside and then vanishing again.
He then discovered he was taken to a strange world, not quite like his own - there were strange creatures, obstacles and gems to collect, so he went around collecting these gems and finding these portals in the hopes that one of them just might take him back home.