As the question and accepted answer in this thread explain, there are a number of possible meanings that pronominal verbs can carry. Now I understand that you're wondering how you can map a given verb to its pronominal meaning. Short answer: there's no failsafe way to do so. Ultimately, you have to learn pronominal verbs via their own dictionary entries to verify the meaning. On the fly, however, here are the strategies I usually use, before "polishing" the result. Mileage may vary.
- See if the transitive meaning can be understood reflexively.
« Je me vois dans le miroir. »
→ Voir : to see
→ Guesses for se voir : to see oneself
→ Best guess: "I see myself"
- If context forbids, see if the transitive meaning can be understood reciprocally.
« Ils se voient tous les trois jours. »
→ Guesses for se voir : to see oneself ; to see each other
→ Best guess: "They see each other"
- If context still forbids, see if the verb makes sense with a passive or "verb-able" meaning.
« Le soleil se voit à travers les nuages. »
→ Guesses for se voir : to see oneself ; to see each other ; to be seen ; to be visible
→ Best guess: "The sun is seen" or "The sun is visible" depending on context
Now we're through with the "literal" meanings (those whose translations can be explained word for word). The reason I started with them is that I'd say one of the above will work for the majority of verbs that are transitive in both English and French — and for that reason they won't all be listed in dictionaries, because they can be deduced in a straightforward way from the non-pronominal verb.
After that, you start to allow more tolerance of figurative meanings.
- Try a reflexive meaning that maps most naturally to a non-reflexive verb in English. Might be particularly common for verbs indicating movement.
« Je me couche à 21h chaque nuit. »
→ Coucher : to sleep ; to spend the night ; to lay down ; to put to bed
→ Guesses for se coucher : to lay oneself down ; to put oneself to bed
→ Best guess: "I lie down" or "I go to bed" depending on context
Other examples: s'asseoir, se lever, se diriger
- Or a passive meaning that maps most naturally to a non-passive verb in English. I find this is often viable for verbs communicating an emotional state.
« Je me fâche. »
→ Fâcher : to anger, to vex
→ Guesses for se fâcher : to anger oneself ; to anger each other ; to be angered
→ Best guess: "I'm angered" → "I become angry"
Other examples: s'irriter, s'étonner
- After exhausting those options, you can tentatively try to simply delete the pronoun in translation. I think this works pretty well when the subject is in some way affected by the verb, and/or the verb is followed by de.
« Je me moque de lui. »
→ Moquer : to mock (literary only, but a good start because of the English cognate)
→ Guesses for se moquer : to mock oneself ; to mock each other ; to be mocked ; to mock
→ Best guess: "I mock" (in theory we could have wrongly guessed "I'm mocked by him", considering Je m'étonne de lui, but hopefully context would rule it out)
Other examples: s'échapper, s'apercevoir, se méfier
- Finally, when neither changing the verb along one of these lines nor deleting the pronoun yields any sense, you have to resort to using a dictionary.
« Elle se bat. »
→ Battre : to beat ; to defeat
→ Guesses for se battre : to beat oneself ; to beat each other ; to be beaten ; to beat
→ The context is likely to rule out all of the above, given the dictionary meaning: "She fights"
Other examples: s'agir de, se débrouiller
So that's more or less the process I'd use. If none of them worked, I'd allow a little more figurativeness to work into my guesses. (For example, « Ça se voit » : "It shows" rather than "It's visible".)
And at the end of the day, I'd still check in a dictionary. I mostly use the above strategies if I'm reading a book and don't want to keep pausing to look things up. Otherwise the dictionary is probably faster. :)