Она редко красится ярко, но перед концертом всё-таки делает лёгкий макияж.

Because краситься is a reflexive verb, formed with -ся. In this sentence, it means to put on makeup / to make oneself up.

• Она красится = She puts on makeup / she does her makeup
• Она красит usually needs an object and means she paints / she dyes / she colors something

For example:

• Она красит волосы = She dyes her hair
• Она красится = She is putting makeup on herself

So here -ся shows that the action is directed toward herself.

They are similar, but not identical.

• красится is a general verb meaning to put on makeup
• делает макияж literally means does makeup, and often sounds a bit more deliberate or specific

In this sentence:

• Она редко красится ярко = She rarely makes herself up brightly
• но перед концертом всё-таки делает лёгкий макияж = but before a concert she does put on light makeup

So the first part talks about her general habit or style, while the second part describes what she does in a particular kind of situation.

Because it describes how she puts on makeup, not what kind of makeup it is.

• ярко = brightly
• It modifies the verb красится

So:

• красится ярко = puts on makeup brightly / wears bright makeup

If you used an adjective, it would have to describe a noun:

• яркий макияж = bright makeup

That is why Russian uses:

• Она редко красится ярко not
• Она редко красится яркая

Because лёгкий describes the noun макияж, so it must be an adjective.

• лёгкий макияж = light makeup
• легко is an adverb meaning easily or sometimes lightly in other contexts, but it cannot describe the noun макияж here

So:

• лёгкий = adjective, agrees with макияж
• макияж is masculine singular nominative
• therefore: лёгкий макияж

After перед in the meaning before/in front of, Russian uses the instrumental case.

So:

• концерт → nominative
• перед концертом → instrumental

Here it means before the concert.

Other examples:

• перед уроком = before the lesson
• перед встречей = before the meeting
• перед сном = before sleep / before going to bed

Всё-таки means something like:

• after all
• still
• nevertheless
• in the end

In this sentence it adds a sense of contrast:

• she rarely wears bright makeup,
• but before a concert she still does put on some light makeup

It suggests: even though she usually avoids strong makeup, there is an exception in this situation.

It most naturally sounds like a habitual statement.

Both verbs are in the present tense and describe what she generally does:

• Она редко красится ярко = she rarely wears bright makeup
• но перед концертом всё-таки делает лёгкий макияж = but before a concert she does wear light makeup

So the sentence means something like: As a rule, she doesn’t wear bright makeup, but before concerts she still puts on light makeup.

If you wanted one specific concert more clearly, Russian would often add context or use past/future forms.

The imperfective is used because the sentence describes habitual, repeated behavior, not one completed event.

• краситься imperfective = to be putting on makeup / to put on makeup regularly
• делать imperfective = to do, to make, in a repeated or general sense

Since the meaning is about what she generally does, imperfective is the normal choice.

A perfective verb would suggest a single completed action in a specific instance, which is not the main point here.

Yes. Наносит лёгкий макияж is also correct and can sound a bit more precise or formal.

• делает макияж = does makeup
• наносит макияж = applies makeup

Both are natural, but делает макияж is very common in everyday speech.

Because но means but, and in Russian it joins two clauses. Russian normally puts a comma before coordinating conjunctions like но when they connect separate clauses.

Here the clauses are:

• Она редко красится ярко
• но перед концертом всё-таки делает лёгкий макияж

So the comma is required.

Yes. Редко usually goes before the verb or near the part it modifies, and Она редко красится ярко is completely natural.

It means:

• She rarely puts on bright makeup

You could sometimes change word order for emphasis, but the given order is neutral and standard.

Yes, it is natural. It means she makes herself up in a bright, noticeable way.

Russian often uses an adverb with краситься:

• ярко краситься = to wear bright makeup
• скромно краситься = to wear modest makeup
• сильно краситься = to wear heavy makeup

So редко красится ярко is a normal way to express that she rarely uses bright or bold makeup.

The main stresses are:

• Она́
• ре́дко
• кра́сится
• я́рко
• но
• пе́ред
• конце́ртом
• всё-таки
• де́лает
• лёгкий
• макия́ж

A learner should especially notice:

• кра́сится
• конце́ртом
• макия́ж

These are easy places to make stress mistakes.