When can one create a "zusammengesetzes Nomen"? When should one use genitive or prepositions instead?

Question

Long words is one of my favorite features in German. Is there a criterion, "eine grammatische Empfehlung!, to know when we can put nouns together?

I'm not talking about creating significant words like "Glühbirne" or "Pusteblumen", don't even care if they are going to be used. I just want to know when it is correct, and when it is better than using Genitiv, prepositions or Relativsätze instead.

1. Importbananen instead of Bananen zu importieren, Bananen, die man importiert.
2. Erziehungcampseinrichtung instead of Einrichtung der Erziehungcamps or Einrichtung von Erziehungcamps.

Does the answer rely on how often they are going to be used in the text?

Context: (read this text if the question wasn't clear enough.) I was writing a text, a little essay without other value than exercising German. I had to mention some "Verhütungsmaßnahmen gegen Jugendkriminalität". I have a very good teacher, and she always corrects minimal details and improves sentences whenever there is a better way to write. I was surprised when my word "Jugendkriminalitätsverhütungsmaßnahme" was not rejected after she read my text. I don't know if she overlooked it, she didn't even understand, or if I was indeed allowed to write that nonexistent word. In any case, I think that the question makes sense.

Answer 1

You can build “zusammengesetzte Nomen” which are as long as you want. One example for that (we played around with that in elementary school) is the “Oberweserdampfschifffahrtskapitänskajütentür”. So your “Jugendkriminalitätsverhütungsmaßnahme” is perfectly fine.

That said, as a native German speaker, I would probably not use this word. It is too long and too hard to grasp on first glance. At least, I would use a hyphen to “mark” the two parts of the word (“Jugendkriminalitäts-Verhütungsmaßnahme”) but more likely I would split it into “Verhütungsmaßnahmen gegen Jugendkriminalität”.

So in the end, it is definitely correct and you can use it. It's just that the other variant is easier to read and grasp.