Some common rules seem to emerge: avoid hybrid words, use connecting vowels in compounding, chose the specifically appropriate word(s) to adapt, there seems to be a preference for compounding (unsure about this), and the Vatican seems to prefer phrases to compounds as do others.
It seems that hybrid words may not be preferable in Greek and Latin neologisms, at least those that are created for use within those languages.
There are connecting vowels for compunding:
The connecting vowel is an element of word structure that is found in words of mostly Latin and often Greek origin. For example, the second in is a connecting vowel between the two bases and .
The vowel letters , , and can all function as connecting vowels.
Words of Greek origin almost exclusively use the connecting vowel <−o−>.
Connecting vowels are structural in origin and have an etymological source. They also often reflect in spelling how words have developed their current spoken English form.
Connecting vowels often replace a final silent in the preceding base or stem.
I've also seen "i" given as the preferred connecting vowel for Latin.
There is also being specific in the word choice:
The phrase “world wide” means something specific in English: across the entire world. There is a phrase for that in Latin: totius terra. The word “web” could also be translated many ways, but the best choice turns out to be tela. Thus, we get tela totius terrae as “web of the entire world.”
Compounding is the combination of two words, often an adjective followed by a noun (not a hard rule). This is just anecdotal observation on my part - I'm not sure how to demonstrate a solid preference for it.
The Vatican publishes the Lexicon Recentis Latinitatis, their take on ways to refer to things not described Latin. While many of the above words are from the Italian, you can see some loan words such as:
Original word: vodka
Latin phrase: válida pótio Slávica
And so on. I'm sure there's more out there on this, though.