The Quran is a sacred book that was revealed to the Prophet Muhammad (peace be upon him) over 23 years. It is indeed a source of inspiration and guidance for all Muslims around the world. 

Since it is considered the holy book of Islam, it must be recited with respect and dignity. Thus, there are several etiquette that you must follow in order to recite the Holy Quran the way it should be recited –

Some scholars suggest that it is important to sit up straight while reciting the Quran and be in a state of ablution. Also, facing the qibla and reciting in a place with minimum distractions are other crucial considerations when reciting the book. 

Those with deep understanding are those who, according to the Qur'an, "remember God standing, sitting, and lying on their sides." (3:191) Similar stories of the Prophet (peace and blessings be upon him) reciting the Qur'an while leaning against something are found in Bukhari and Muslims. Therefore, even though state of cleanliness and purity are essential parameters of reciting the Quran, one can sit comfortably and recite too. 

Let us unfold the etiquettes of reading Al Quran Pak one by one –

• Although it is recommended to cover your head while reciting the Quran, it is not mandatory. 
• There is no problem in reciting the Quran while leaning against the wall or headboard. As mentioned above, it is how the Prophet (peace be upon him) used to recite. 
• You do not need to be in an ablution state if you are reciting the Qur'an from memory without touching the real, physical copy. Still, it would be ideal to be in an ablution state. However, one must be in a pure state to read from the Qur'an while holding it.
• Due to the complexity of Arabic, one of the world's most difficult languages, even the slightest pronunciation error can have a significant impact on the meaning of a verse when reciting the Quran. Thus, heed the Tajweed laws to the letter.

Since the Quran is the language of Allah, it is best to recite it the way one should. Therefore, keep in mind these simple etiquette of reading the Quran if you want to maximise the rewards.