I think the only way to choose well is to echo some Latin usage that you already know from some other context. Of course this is how all language works. You choose your words to awaken common experience with those words and grammar and their meanings in your listener. There's an excellent self-teaching book for Latin, Lingua Latina Per Se Illustrata (The Latin Language Illustrated by Itself) which does a nice job of cultivating a feeling for Latin usage and grammar.
Another fundamental of translation is to think of the meaning of the whole sentence or phrase and then think how someone would point out the same thing using the resources of Latin—not to go word by word or even concept by concept. A different language isn't just a different mapping of words to concepts, it's a different way of thinking, a different set of habits for conceptualizing the world. A simple example, also found in the Romance languages, is that you don't "like" something; rather, it "pleases" you—tibi placet.
I just found this translation of a sentence from Tac. Ann. 15.36, which might illustrate several deep differences between how you think and say things in Latin and in English:
Nec multo post omissa in praesens Achaia (causae in incerto fuere) urbem revisit, provincias Orientis, maxime Aegyptum, secretis imaginationibus agitans.
Soon afterwards, giving up Achaia for the present (his reasons were not certainly known), he returned to Rome, there dwelling in his secret imaginations on the provinces of the east, especially Egypt.
If we translate very literally, we can see a variety of illustrative differences:
Nor much afterward, Achaia omitted into the present (the causes were in the uncertain), he (Nero) revisited the city, driving the provinces of the East, Egypt the most, in secret mental images.
You can see here:
Latin makes more use of clauses anchored on participles: omissa (omitted), agitans (driving). In this sentence, most of the action occurs in these subordinate clauses, not in urbem revisit.
The ablative case situates the action of main verb: the ablative absolute omissa... establishes the occasion of Nero's return to Rome; secretis imaginationibus is "where" Nero thinks about the provinces. This way of framing a sentence is very common and familiar in Latin.
A more common idiom for mental deliberation is in animo agere. I think Tacitus substitutes the unusual phrase secretis imaginationibus first to evoke the familiar in animo and, by the variation, to suggest that Nero is embarrassed and/or scheming.
Substantive use of adjectives in fixed phrases: in praesens, in incerto. I think the accusative praesens rather than the ablative praesenti suggests a certain way of thinking about time.
"Bracketing", where a verb or participle stands at the beginning or end of the clause that it governs. Omissa starts the ablative absolute, ending with Achaia, which agrees with it grammatically. The sentence satisfyingly ends on agitans, all the words going back to its object provincias having set it up.
There are more differences that could be pointed out, of course. The main thing to notice for your question is that the various grammatical endings are chosen to evoke and link familiar phrases and patterns, many of which don't exist in English. They make the sentence easy to follow and very expressive for a person familiar with those phrases and patterns. And of course that's how to choose your words and grammar in Latin.
(I'm not an expert on Latin, so please don't give too much weight to the above examples without checking them out yourself.)