Where can I find a list of ways to get rid of the preposition "of"?

"Of" can be alternated with possessives and adjectives. (quality of approach and variety of sentences) "This approach's quality can be improved by using sentence variation in order to enhance vocabulary and style."

You really need to consider not two, but three forms:

1. word memorization

2. memorization of (the) words

3. memorizing (the) words

In all but technical writing, 3) is much the most common. (Personally I would prefer it even in technical writing, but some people seem to think that abstract nouns make their writing more impressive.)

Sentence 2 is unusual in any context, unless the topic is the memorization, and "of the words" is almost incidental, eg "The memorization of the words was a major feat for this actor" - but even then, 3. would be more natural for me.

[Note: I've put (the) in parenthesis because 2. and 3. are grammatical both with and without 'the', but the meaning is different. 1. is ambiguous in this respect - another reason why I would avoid it. ]

Edit: just noticed that SE renumbered my "2." to "1.", making my last paragraph before the note into nonsense. Corrected by adding the word "Sentence" to protect my "2" from its evilhelpful clutches.