As a beginner in translation (actually it is less than a year since I've started this career), I'm looking for a few books for reference and to enhance my knowledge and improve my skills in grammar, in general, as sometimes my translated works are corrected by a native proofreader (especially when I translated religious book) when I translated from Thai to English (but it is fine when I translate from English to Thai)

I am struggling the most about how to use preposition, and I am still not that good at picking a word to from word choices. (as I was complained by the native proofreader). And there may be some other issues like which VS that, comma, and so on.

I am interested in legalese as well since some of my Thai-to-English translation works are legal contract and other official letters.

Is the Garner's Modern American Usage, andOxford Collocations Dictionary good?
Any suggestion is welcomed! Electronic format is fine for me as well. (I have to travel for a week almost every month)

Thank you in advance.