There is no harm for a fasting person to taste food as needed. If they accidentally swallow it, there is no sin, and they can continue their fast.

If a fasting person swallows his saliva, that does not invalidate his fast even if there is a lot of it.

If a man kisses his wife whilst he is fasting and emits maniy, then he has invalidated his fast and he has to make up that day’s fast after Ramadan ends.

If you rinse your mouth or nose while fasting and some of the water goes down into your throat without you intending it, that does not break the fast.

Some Sunnahs of fasting: 1- If someone reviles you, respond to him by saying ‘I am fasting.’ 2- Eating Suhur. 3- Hastening to break the fast and delaying Suhur. 4- Breaking the fast with fresh dates. 5- Saying this du`a when breaking your fast: ‘Dhahaba al-zama-u wa abtalat al-‘uruqu wa thabata al-ajr in sha Allah.’ 6- Offering a lot of du`a.

The fast that was done with the intention of observing a voluntary fast cannot count as a fast observed to make up for a missed obligatory fast.

If you start an obligatory fast, such as making up a missed Ramadan fast or offering expiation for breaking a vow, it is not permissible for you to break the fast without a valid excuse, such as sickness or travel.

It is not allowed to anticipate Ramadan by fasting one or two days before it begins for those who do not have a habitual pattern of fasting or who are not continuing to fast after starting to fast before (in the first half of Sha`ban).

Fasting on the two days of Eid is haram. It is also haram to fast on the days of al-Tashreeq which are the three days after Eid al-Adha.