How would I go about with a level selection screen?
Such as after finishing level 1, level 2 will be unlocked and so on.
I’ve done this before by using a ton of booleans, but it feels like there is a faster and easier way to do this, so the main question is. How could I accomplish a level selection screen without the use of numerous booleans to check if level one is completed or not and such.
Can anyone lead me into a good start and what to use?
The best way might be to have a controller script track which the last level that a player completed. That’s one int instead of a list of booleans. Whenever you complete a level, and before you call Application.LoadLevel, just set that static int in your controller. Then, on the level select screen, query that int’s value and unlock n+1 levels! 
Of course, you’re going to want to serialize that value to PlayerPrefs or XML or binary; which ever you’re using.