Tazkiah (تزكية) is an Arabic-Islamic term alluding to "tazkiyah al-nafs" meaning "sanctification" or "purification of the self". This refers to the process of transforming the nafs (carnal self or desires) from its deplorable state of self-centrality through various spiritual stages towards the level of purity and submission to the Will of Allah.
I have a tutorial on this, where you are able to see in practice how this is done:
Proper thinking and sincere devotion to the truth lead the person to be a good person obeying Allah, The Creator, The Most Merciful. All our needs, hopes and wishes are in His Hand and He is everything in our life here and hereafter.
When we think rationally with perfect logic, we know that every act , good or bad has a result, whether it is good or bad. We are more near to the truth when we think properly and ponder of our life start, present and future and our actions. We don't have any supporter more Able, Merciful on us than Our Creator Allah. No one knows about us more than Him. No one is more close to us than Allah (SWT). Being with Allah (SWT) is the only way for peace and tranquility and the only way for happy and successful life here and hereafter. Imam Husain(AS) was reported supplicating to Allah: O Allah; Who found you,what did lose? And who lost you,what did he get?
You may read Quranic verses as much as you can and the supplications of Kumayl, Abu Hamza al-Thimali, and Saheefa Sajjadia and other supplications and sayings narrated from The Prophet (SAWA) and Ahlul Bayt(AS).
Just wash your hands with water, one time if water is connected to tab or big quantity, and two times if water is in small quantity. Obviously, no Najis material should be on your hands.
If the washing machine is connected to the tab water, then it will be Taahir along with all the clothes inside it. If there is no connection with tab water or any Kurr water, and water used is less than Kurr, then Najis cloth will remain Najis unless it is washed and rinsed twice with Taahir water.
There are many books on this subject, but not all of them are translated in English.
One of the well known books which are translated in English is Jami' Al-Sa'adaat by Al-Naraaqi (The Collector of Felicities).
You may also see Mir'aat Al-Rashaad مراة الرشاد by Shaikh Abdullah Al-Mamaqani.