Learn Italian: Dopo il liceo, scelgo la facoltà di medicina. - After high school, I choose the faculty of medicine.

If the reporting verb is in the past, the present tense scelgo shifts back one tense to the imperfetto. You would say: Lui ha detto che dopo il liceo sceglieva la facoltà di medicina (He said that after high school he chose the faculty of medicine).

The infinitive is scegliere. Why does scelgo have a hard 'g' sound?

Scegliere (to choose) is irregular. The io and loro forms drop the soft gli sound and use a hard g instead: io scelgo and loro scelgono. The other forms keep the soft sound, like tu scegli.

Is liceo a false friend for the English word 'college'?

Yes, liceo refers to an academic high school in Italy, not a university. To talk about college or higher education, you would use l'università.

Why is it di medicina instead of della medicina?

When naming a specific university faculty, degree, or subject of study, Italian uses the simple preposition di without the definite article.