The plateau nobody warns you about
There is a point where your Portuguese works. You can hold a conversation, follow a film, argue about parking. And you still sound wrong, in a way you cannot quite locate.
The reason these errors survive is that they do not stop anyone understanding you. Nobody corrects them, because correcting them would be rude and the meaning came through anyway. So they set. Most of them are fossils from early on: a Brazilian habit picked up from an app, or a Spanish cognate that happened to work once. Five of them are worth hunting down.
1. Softening your t and d
This is the fastest giveaway in Portugal. If you have listened to any Brazilian Portuguese, you know the "chee" and "jee" sounds: dia as "jee-ah", noite as "noy-chee". That softening happens when t and d land before an i or a reduced e.
In Portugal those consonants stay dental. Tongue tip against the back of the upper teeth, hard and sharp. Dia is "dee-ah". Noite is closer to "noyt", the final e barely a breath.
It matters more than it sounds. European Portuguese is built on hard consonant edges, and softening them blurs the staccato that carries the rhythm. To a Lisbon ear the result is mushy. There is also a listening cost, and this is the part people miss: if your internal map of the sounds is palatalised, you spend the whole conversation waiting for "chee" sounds that nobody in the room is producing.
Say the English word "tea", then "deep". Notice where your tongue goes. Now put it in the same place for tio, cidade, sentir.
2. Pronoun placement, and the words that pull
By this stage you can put the pronoun after the verb without thinking: Amo-te, Vi-o. The harder question is when to move it in front.
Certain words drag the pronoun forwards. Everybody learns the obvious one, não, as in Não te amo. Subordinate clauses are where it falls apart.
Take "I hope we see each other tomorrow."
What advanced learners say: Espero que vemo-nos amanhã.
What it should be: Espero que nos vejamos amanhã.
Que pulls hard. Almost anywhere it turns up, the pronoun goes to the front, and the same is true of question words (Quem te disse?) and some adverbs (Também o vi).
Get it wrong and the sentence sounds off-beat rather than incorrect, which is exactly why nobody flags it. Reading is the cheapest fix. Not reading for meaning, though: read a page hunting only for the words doing the pulling, and after a few pages you start to feel them coming.
3. Reaching for você
In Brazil você is the friendly, ordinary way to say "you". In Portugal it sits in an awkward middle ground. Cold to some ears, faintly condescending to others, and almost never neutral.
The way out is to drop the pronoun. Use the third-person verb form on its own and let the ending do the work.