Learn Hardcore Portuguese (Portugal): Quero ser mais consciente quando uso dinheiro. - I want to be more aware when I use money.

Quero ser mais consciente… = “I want to be more conscious…” (about myself, my behaviour).
It does not sound rude in this context, because you’re not asking anyone for anything; you’re just stating an intention.

If you were making a polite request to someone (e.g. in a shop or restaurant), you would normally soften it, for example:

Queria… / Gostava de… = “I’d like…” (more polite / tentative in requests)

But for talking about personal change, Quero ser mais consciente… is completely natural.

Why is it ser and not estar in Quero ser mais consciente?

Portuguese uses ser and estar differently:

ser = more permanent or characteristic state (identity, personality, long‑term qualities)
estar = temporary or changing state (moods, locations, current situation)

Quero ser mais consciente suggests a lasting trait or habit: you want to be a more conscious / aware person when dealing with money.

Quero estar mais consciente would sound more like “I want to be more aware (at that particular moment / temporarily)”, which doesn’t fit as well with the idea of an ongoing new attitude or habit. That’s why ser is the better choice here.

What exactly does consciente mean here? Is it like English “conscious” or “aware”? And does it change for gender?

In this sentence, consciente means “aware / mindful / responsible”, not “awake vs. asleep”.

ser consciente (of money, the environment, etc.) = being aware of impact, acting thoughtfully, being responsible.

About forms:

Masculine singular: consciente (e.g. um homem consciente)
Feminine singular: consciente (e.g. uma mulher consciente)
Plural (both genders): conscientes (e.g. pessoas conscientes)

So the form consciente in Quero ser mais consciente works for both “I” (masc.) and “I” (fem.); your gender doesn’t change the word.

Should it be quando uso dinheiro or quando usar dinheiro if I’m talking about the future?

Both are possible, but they have slightly different nuances:

quando uso dinheiro = “when(ever) I use money” in a general, habitual sense (whenever that happens, in general).
- This fits if you mean a general pattern: any time I use money, I want to be more conscious.
quando usar dinheiro uses the future subjunctive (usar), which is very common in Portuguese after quando, se, etc. for future events:
- Quero ser mais consciente quando usar dinheiro.
- Nuance: “I want to be more conscious whenever I will use money (from now on).”

In everyday speech, many people would actually prefer quando usar dinheiro here, because the sentence is about future behaviour. But quando uso dinheiro is also grammatically correct if you mean “as a rule, whenever I use money”.

Could I say quando gasto dinheiro instead of quando uso dinheiro? Is one more natural?

Yes, and for this idea quando gasto dinheiro is often more natural.

usar dinheiro = to use money (quite general: handle it, use it for something)
gastar dinheiro = to spend money

If what you really mean is “spending money more carefully”, then:

Quero ser mais consciente quando gasto dinheiro.
sounds very natural in European Portuguese.

Quando uso dinheiro is not wrong, but it’s a bit more neutral and broad; it doesn’t focus as clearly on spending.

Why is there no article in uso dinheiro? When would I say uso o dinheiro?

Portuguese often drops the article with unqualified mass nouns (like “money”, “milk”, “water”) when you’re talking about them in general:

uso dinheiro = “I use money (in general)”
bebo água = “I drink water”

You add the article o / a / os / as when you mean specific, identified money:

uso o dinheiro que ganhei ontem
= I use the money that I earned yesterday (that particular money)

In your sentence, you’re talking about money in general, so uso dinheiro is the natural choice.

Can/should I include eu, as in Eu quero ser mais consciente…?

You can, but you don’t need to.

Portuguese verb endings show the person, so quero already tells us it’s “I”.
Quero ser mais consciente… is the normal everyday form.

You add eu mainly for emphasis or contrast:

Eu quero ser mais consciente, mas eles não querem.
= I want to be more conscious, but they don’t.

So in isolation, Quero ser mais consciente quando uso dinheiro is perfectly natural without eu.

Why is it mais consciente and not consciente mais? Where does mais go?

With adjectives, mais (meaning “more”) normally goes before the adjective:

mais consciente, mais responsável, mais cuidadoso

So:

Quero ser mais consciente ✅
Quero ser consciente mais ❌ (ungrammatical)

You can stack it with other words of degree, still before the adjective:

Quero ser muito mais consciente
Quero ser um bocadinho mais consciente

Is there a more idiomatic or common way to say this in European Portuguese?

Your sentence is correct, but some alternatives might sound even more natural in everyday European Portuguese, depending on the nuance you want:

Quero ser mais consciente com o dinheiro.
(very close to yours; just com o dinheiro instead of quando uso dinheiro)
Quero ser mais responsável com o dinheiro.
(emphasises responsibility)
Quero ter mais cuidado com o dinheiro.
(very common, sounds like “I want to be more careful with money.”)

All of these would be idiomatic in Portugal.

How is Quero ser mais consciente quando uso dinheiro pronounced in European Portuguese?

Approximate European Portuguese pronunciation (stressed syllables in CAPS, rough English hints):

Quero → KE-ru
ser → sehr (short e, like set)
mais → maish (like mysh)
consciente → kon-si-EN-te (final -e is very reduced, almost like a weak “uh”)
quando → KWAHN-du (first a is nasal, like French en)
uso → OO-zoo
dinheiro → dee-NYEH-ru (the nh is like Spanish ñ in niño)

Said smoothly: KE-ru sehr maish kon-si-EN-te KWAHN-du OO-zoo dee-NYEH-ru.