"Se llegó a ser director." I see this one a lot. Every other verb of change takes se, so learners add it here too. Hacerse and llegar a ser both mean "became", and both are about a path you chose. The difference is the climb. Hacerse is the step: se hizo abogado, he became a lawyer. Llegar a ser is where you end up after years of work. Llegó a ser socio del bufete. = He worked his way up to partner at the firm. And it's the one that never takes se. Llegó, not se llegó.

"Me puse enfadado." Grammatically it holds up. Hardly anyone says it, though. English builds the change with "get": get angry, get tired, get bored. So learners grab ponerse every time. But Spanish usually has the change packed into a reflexive verb already. Enfadarse doesn't mean "to be angry", it means "to get angry". Me enfadé mucho. = I got really angry. Same with cansarse, aburrirse, asustarse. Before you build "get + adjective" with ponerse, check whether the verb already exists.

"He got sad" and "he became sad" sound close in English. In Spanish they need two different verbs, and the question that picks one is how long the change lasts. Se puso triste. He got sad (this afternoon, he'll be fine tomorrow). Se volvió triste. He turned into a sad person. Ponerse is a passing state: mood, nerves, going red. Volverse is a change in who someone is, and usually one nobody chose. Same adjective, and the verb alone tells you if it was a bad day or a bad few years.

Ask a learner to say "I met María in 2019" and you usually hear "Encontré a María" or "Me reuní con María." The first means you found her or ran into her. The second sounds like a work meeting. Spanish says: Conocí a María en 2019. Conocer is knowing a person. The preterite points at the moment something started, and the moment you start knowing someone is when you meet them. Saber does the same trick. Supe la verdad ayer: I found out the truth yesterday. Same verb, but in the preterite it's the second the knowing began.

Ask a learner if they liked the paella and a lot of them say "Sí, muy." Or "Me gustó muy." That muy has nothing to hold on to. Muy only works right before an adjective or an adverb: muy rica, muy bien. It can't stand alone, and it can't go with a verb. The trap is English "very much." Spanish drops the "very" and lets mucho do all the work: Me gustó mucho. (I liked it a lot.) And the short answer is just "Mucho."

Most learners choose between comí and comía by asking whether the action finished. But everything in the past finished. That question can't help you. Ask this instead: is it the event, or the scenery around it? Estaba comiendo cuando llamaste. (I was eating when you called.) The eating was already going on. It's the backdrop, so it takes the imperfect. Your call is what actually happens in the story, so it takes the preterite.

Most learners say "pedí por un café" at some point. The por is doing nothing there, and it is the English leaking through. English has ask and ask for. Spanish cuts it in a different place: pedir is for things you want, preguntar is for things you want to find out. The "for" already lives inside pedir, so por has no job. Pedí un café. (I asked for a coffee.) Le pregunté si venía. (I asked her if she was coming.) The test is what comes back to you. An object or an action, pedir. Information, preguntar.

Most learners say "Me olvidé las llaves." That works. But listen to a native speaker who just locked themselves out: "Se me olvidaron las llaves." Look at the verb. Olvidaron is plural, and that's the whole trick. The subject isn't me anymore, it's the keys. I'm just the person it happened to, that little "me" in the middle. Se me olvidaron las llaves. = My keys slipped my mind. So the grammar quietly moves the blame. Nobody did anything, it just happened, and I'm the one stuck outside. Same thing with se me cayó el móvil or se me rompió el vaso.