Learn Spanish (Latin America): Trato de comer bien.

In Spanish, the verb tratar meaning 'to try' or 'to attempt' must be followed by the preposition de when you are trying to do an action. English uses 'to', but Spanish requires this specific verb-preposition combination: tratar de.

Could I use pruebo instead of trato here?

No. While both verbs translate to 'try' in English, they are used differently. Tratar de means to attempt an action. Probar means to test something out or to taste food. Since you are attempting the action of eating well, you need trato de.

Why is comer left in the infinitive (unconjugated) form?

In Spanish, whenever a verb immediately follows a preposition like de, a, en, or con, it stays in its infinitive form. Since it comes right after de, we use comer.

Why use bien instead of bueno?

Bien translates to 'well' and describes how you do an action (like eating). Bueno means 'good' and is used to describe nouns (like a good meal). Since you are describing how you eat, you must use bien.