Firstly: Hastening to Breaking the Fast
It is sunnah for the fasting person to hasten in breaking his fast as soon as he is certain in the sun setting. Consensus has been quoted on this matter by: Ibn Rushd, Ibn Daqiq al-`Id, Ibn Muflih, and al-Mardawi.
Secondly: The Ruling of Breaking the Fast Based on High Likelihood
It is permissible for a fasting person to break their fast if they believe it is most likely the case that sunset has occurred. This is by agreement of the four schools of jurisprudence.
Thirdly: What to Break the Fast With
It is mustahabb to break the fast by eating ripe, soft dates; if not, then dry dates; if not, then water.  Whoever finds no moist or dry dates or water, then he breaks his fast on what is available of food or drink. Whoever has no food or drink available, intends to break his fast silently, does not need to suck his finger or collect his saliva and swallow it as some do. This is the position of the majority: Malikis, Shafi`is, and Hanbalis.
Fourthly: Utterances when Breaking the Fast
When breaking the fast, it is sunnah to say: "Thirst has gone, the veins are rejuvenated, and the reward is established, by the will of Allah."
Fifthly: The Ruling of the Pre-Dawn Meal  Sahur is food and drink consumed at the time of sahar, before twilight. Suhur is the consumption of said food and drink.
It is mustahabb for the one who intends to fast to have a pre-dawn meal. Consensus has been quoted on this by: Ibn al-Mundhir, al-Qadi `Iyad, Ibn Qudamah, al-Nawawi, and al-`Ayni.
Sixthly: Delaying the Pre-Dawn Meal
It is sunnah for the one who intends to fast to delay his pre-dawn meal as long as he does not fear the entering of fajr. Consensus has been quoted on this by: Ibn Rushd, Ibn Muflih, and al-Mardawi.
Seventhly: What Qualifies as a Pre-Dawn Meal
Any food or drink, in small or large quantities qualifies as a pre-dawn meal.
Eighthly: What is Sunnah to Have for the Pre-Dawn Meal
It is sunnah to have dry dates for the pre-dawn meal.
Ninthly: Avoiding Impermissibilities and Engaging in Obedience
The fasting person should avoid haram acts, like back biting, gossiping, lying, cheating, mocking others, listening to music, and looking at indecency. All this affects the fast and decreases its reward.
He should likewise busy himself with devotional acts of worship as he has kept himself away from what is normally permissible. He should engage in reciting the Qur'an, uttering words of remembrance, supplication, prayer, and being good to others.
Tenthly: What the Fasting Says to the One Who Insults Him
In the event he is insulted or attacked, the fasting person should say aloud:  Ibn Taymiyyah said: “What is most correct is that he says this with his tongue, since unconditional statements are with the tongue, and those in oneself are conditional.” Minhaj al-Sunnah al-Nabawiyyah (197/5) "I am fasting."
Eleventhly: What the Fasting Person Does if Invited to Eat
If the fasting person is invited to eat food while fasting, he says: "I am fasting." This is regardless whether the fast is wajib or voluntary. He also supplicates for the one who invited him. If his refusing the invite causes difficulty for the one who invited him, then he breaks his fast if it is voluntary, but it is haram to break it if it is wajib.