What is chitta ? How can we purify it to make our life and afterlife peaceful?

Question

How should we purify chitta so that our death and time after death can't be harmful or full of suffering for us.
How someone can get peace with it?

Answer 1

Chitta means mind in general. Mind itself can be categorized into many subtler parts like Manas, Buddhi etc.
Food eventually transforms into the mind (I don't recall exact shastra quote for this, but it exists)

So, to purify chitta, answer is simple : clean (meaning satvik) food = clean chitta

Chandogya Upanishad :

आहार शुद्धौ सत्त्व शुद्धिः सत्त्व शुद्धौ ध्रुव स्मृतिः
ध्रुव स्मृति-लम्भे सर्व ग्रन्थीनां विप्र मोक्षः

Ahara suddhau sattva-suddhih Sattva-suddhau dhruva smrtihi
dhruva smrti-lambhe sarva-granthinam vipra-moksah

From purity of food, follows purity of mind.
Pure mind -> Firm memory -> Knots (of samsara) are loosened -> Wise get liberated.

Krishna also says:

ayuh-sattva-balarogya- sukha-priti-vivardhanah
rasyah snigdhah sthira hridya aharah sattvika-priyah

“Foods dear to those in the mode of goodness increase the duration of life, purify one’s existence and give strength, health, happiness and satisfaction. Such foods are juicy, fatty, wholesome, and pleasing to the heart.”

So.. I said it is simple, but it is not at all easy.. what are exactly are Satvik foods ? Krishna mentioned this only in very general terms in Gita.
Whereas, there is an entire grantha Ahara Niyama that mentions exact fruits/vegetables/milk we cannot eat, when to eat, how to eat, who should serve it etc.

Some samples:
- Avoid liquor
- Avoid meat
- Avoid eating in restaurants
- Avoid onion, garlic, mushrooms, drumstick, watermelon, white brinjal etc.
- Avoid milk taken from cow whose own calf is not nearby or was not fed by it , the milk for first 10 days after it gave birth, or milk from pregnant cow .. most milk available in cities nowadays does not meet these requirements, you have to go to goshala for satvik milk
- Avoid tea, coffee, soda
- Avoid eating before bathing, or at dusk, or at midnight, or while standing, or with left hand
- Avoid food that is ucchishtam (no sipping drinks or licking fingers, because saliva has already transferred from mouth to that food) - exceptions are ucchishtam of one's father, eldest brother, or acharya
- Avoid husband and wife eating together (wife should serve husband first)
- Avoid food seen by immoral people and food touched by sanyasi
- Avoid food with hair or nails in it, and avoid food fallen on cloth
- Avoid food kept separately for oneself before serving guests
- Avoid food on Ekadashi

Most importantly
- Avoid food not offered to God

Answer 2

You are clearing chitta requires a lifestyle change food affects mind. You need to have positive thoughts towards Lord God is grateful. He will guide us if we remember him. You think of him doing anything daily activities offer your karma. Meditate on him think about Lord sleeping and waking. Chitta will be purified. It also depends on your spiritual evolution.