1. Sleep in a state of taharah
(purity).
Ibn Abbas 
reported that Allaah's Messenger 
said: “Purify these bodies and Allaah will purify you, for there is
no slave who goes to sleep in a state of purity but an Angel spends the
night with him, and every time he turns over, [the Angel] says, 'O Allah!
Forgive Your slave, for he went to bed in a state of purity.'” [Reported
by at-Tabaranee. See Saheeh al-Jamee (3831)]
2. Sleep early.
Sleeping early is a healthy habit and it was the
practice of Allaah's Messenger
to sleep directly after performing the Isha prayer. Abu Barzah al-Aslami
said that the Prophet
used to prefer to delay Isha, and he
did not like to sleep before it or talk after it.” [Saheeh al-Bukharee]
3. Choose a suitable bed.
Excessive luxurious or soft bed provokes laziness
and makes one sleep more and become negligent. Aa'ishah 
narrates that the pillow of the Prophet
on which he slept at night was made of leather stuffed with palm fibers.”
[Abu Dawood and Musnad Ahmad. Saheeh al-Jamee
(4714)]
4. Clean the bed and lie on the right side.
Abu Hurayrah
reported: The Prophet
said: “When any one of you goes to bed, let him clear his bed by hitting
it with his garment, for he does not know what may have come onto it. Then
let him lie down on his right side…” [Saheeh al-Bukharee and Saheeh
Muslim]
5. Reciting the Adhkaar (supplications) mentioned in the Sunnah before sleeping.
There are a number of Adhkaar prescribed in the Sunnah before going to bed, amongst them are reciting the last verses of Surah Al-Baqarah Verse 285 and Verse 286], reciting Surah Al-Falaq, Surah An-Nas and Surah Al-Ikhlas , blow in the palms and wipe as much of the body possible, starting from the head, face and then the front of the body doing it three times. [Saheeh al-Bukharee and Saheeh Muslim]
Ali Ibn Abi Talib
reported that when the Prophet's
daughter, Fatima
came to him and asked him for a servant, he
said to her and Ali: “Shall I not teach you something that will be better
for you than a servant? When you go to bed, say 'SubhanAllah' thirty-three
times, 'Al-hamdulillah' thirty-three times, and
'Allahu Akbar' thirty-four times. This is better
for you than a servant.” [Saheeh al-Bukharee
and Saheeh Muslim]
