Я редко крашу ресницы тушью, а помадой пользуюсь только по праздникам.

Because with the verb красить in the sense of to color / to paint / to put makeup on, the thing you use is often put in the instrumental case.

So in:

крашу ресницы тушью

• ресницы = the thing being affected (eyelashes), so it is the direct object
• тушью = the means/tool/material (with mascara), so it is instrumental

This is similar to:

• красить губы помадой = to paint one’s lips with lipstick
• писать ручкой = to write with a pen

The dictionary form is тушь, and the instrumental singular is тушью.

For a similar reason: пользоваться normally takes the instrumental case.

So:

• помада = lipstick
• помадой пользуюсь = I use lipstick

This is a very common pattern:

• пользоваться телефоном = to use a phone
• пользоваться словарём = to use a dictionary
• пользоваться косметикой = to use cosmetics

So even though both тушью and помадой are instrumental, they are there for slightly different grammatical reasons:

• тушью because it is the material/tool used with красить
• помадой because пользоваться requires instrumental

Because ресницы is the direct object of крашу.

In Я крашу ресницы:

• я = subject
• крашу = verb
• ресницы = what I am painting/applying makeup to

The noun ресницы is plural. Its dictionary form is also ресницы, and in this sentence the accusative plural looks the same as the nominative plural.

So:

• nominative plural: ресницы
• accusative plural: ресницы

That is why you see ресницы, not ресницами.

Ресницами would be instrumental plural and would mean something like with eyelashes, which does not fit here.

Russian often uses different verbs depending on how natural the action sounds.

• красить ресницы тушью = to apply mascara to eyelashes
• пользоваться помадой = to use lipstick

You can say things like красить губы помадой if you are specifically talking about the act of putting lipstick on your lips. But пользоваться помадой is broader and often sounds more general: to wear/use lipstick as part of one’s routine.

So the sentence has a natural contrast:

• I rarely apply mascara
• and I use lipstick only on special occasions

It is less about strict grammar and more about natural usage.

А often marks a contrast or a shift from one idea to another.

Here the speaker is comparing two habits:

• Я редко крашу ресницы тушью
• а помадой пользуюсь только по праздникам

So а is like:

• whereas
• but
• and as for

It does not always mean a strong contradiction, but it often highlights a difference.

In English, a natural translation would be something like:

• I rarely wear mascara, and I only use lipstick on special occasions
• or I rarely put mascara on my eyelashes, but I only use lipstick on holidays/special occasions

Using и would sound more like simple addition, while а makes the comparison clearer.

Because in Russian, once the subject is clear, it is often omitted.

So:

Я редко крашу ресницы тушью, а помадой пользуюсь только по праздникам.

literally has:

• I rarely paint my eyelashes with mascara
• and lipstick I use only on holidays

The subject я is understood in the second clause from the first one.

You could say:

Я редко крашу ресницы тушью, а помадой я пользуюсь только по праздникам.

But that sounds more emphatic. Normally the shorter version is more natural.

По праздникам means on holidays, on festive days, or more naturally in many contexts, on special occasions.

This is a common Russian pattern:

• по утрам = in the mornings
• по вечерам = in the evenings
• по выходным = on weekends
• по праздникам = on holidays / on festive occasions

So только по праздникам means not in everyday life, but only when there is some celebration or special event.

Depending on context, a natural English translation might be:

• only on holidays
• only on special occasions
• only for celebrations

Because редко is an adverb meaning rarely, and it commonly goes before the verb it modifies.

So:

Я редко крашу ресницы тушью = I rarely apply mascara to my eyelashes

Russian word order is flexible, but this is the neutral and natural order.

Other orders are possible for emphasis, for example:

• Я крашу ресницы тушью редко — possible, but more marked
• Редко я крашу ресницы тушью — strongly emphatic/literary

The original sentence uses the most standard order.

Крашу is imperfective because the sentence describes a habit or repeated action.

Russian normally uses the imperfective for:

• habits
• general facts
• repeated actions
• ongoing processes

So:

Я редко крашу ресницы тушью = I rarely put mascara on my eyelashes

If you used покрашу, that would usually refer to one completed future action:

• Я покрашу ресницы тушью = I’ll put mascara on my eyelashes / I’ll do my eyelashes with mascara

That would not fit the meaning of a general habit.

The same logic applies to пользуюсь: it describes a regular pattern, not a one-time event.

Literally, it is closer to I paint/color my eyelashes, but in natural English that sounds odd. In real translation, it usually becomes:

• I put mascara on my eyelashes
• I wear mascara
• I use mascara

Which English version is best depends on context.

Russian often uses a more concrete verb like красить, while English may prefer a more idiomatic makeup-related expression.

So yes, the literal structure is paint the eyelashes with mascara, but you usually should not translate it word for word.

It is still the instrumental case. In Russian, cases are not only used after prepositions; many verbs require a certain case directly.

Here the verb пользоваться governs the instrumental:

• пользоваться чем? = to use what?

So:

• пользоваться помадой
• пользоваться духами
• пользоваться ноутбуком

No preposition is needed.

This is an important point for English speakers, because English often uses a bare noun after use, but Russian frequently marks that relationship with a case ending instead.

Yes, both are possible, but the meaning and style shift a little.

You can say:

• Я пользуюсь тушью = I use mascara
• Я крашу губы помадой = I put lipstick on my lips

So the sentence could have been built differently. The original version simply chooses two natural expressions:

• крашу ресницы тушью
• помадой пользуюсь

These are both idiomatic. Russian often has more than one natural way to express makeup-related actions, and speakers choose based on nuance, habit, and style.

Most likely yes in terms of real-world context, because the sentence talks about mascara and lipstick. But grammatically, the sentence itself does not show feminine past-tense or adjective agreement, so the verbs do not mark gender here.

Present tense verbs like:

• крашу
• пользуюсь

only show person and number, not gender.

So grammar alone does not tell you the speaker’s gender. The implication comes from the content, not from the verb forms.

The dictionary forms are:

• красить = to paint, color, dye, apply makeup to
• пользоваться = to use

The forms in the sentence are:

• крашу = first person singular present: I paint / I apply
• пользуюсь = first person singular present: I use

Notice that пользоваться is a reflexive verb, so its form includes -сь here:

• я пользуюсь
• ты пользуешься
• она пользуется

That reflexive ending is just part of the verb and must be learned with it.