You may place a siddur or chumash flat on chair seat or bench on which no one is sitting, but it is an act of piety to stand it up on its edge. 
To sit on a bench or other seat where a holy book rests, raise the book up at least a little; a single piece of paper is sufficient elevation.
NOTE If you are sitting on a bench and someone puts a holy book on the bench, you must stand up or raise the book off the bench. You may not stand a siddur, chumash, or other holy book up on its edge on a bench or pew in order to be allowed to sit on that bench.

Each dead person needs kaddish to be said for him or her:

• By at least one person.
  Note If more than one person who was close to the dead person (such as a relative) says kaddish, it is a merit for the soul of the dead person.
• At least once a day. 
  Note More frequently is commendable, since kaddish relieves a dead person's soul from gehenna.

A non-Jew is not permitted to observe Shabbat completely. He or she must do at least one violation. This is relevant for people who are in the process of converting to Judaism.
 

If a boy born in Adar 2 will be bar mitzva in a year with only one Adar, his bar mitzva is in Adar, not in Nisan. If a boy born in Adar 1 will be 13 years old in a year with two Adars, his bar mitzva will be in Adar 2.

We are required to eat two meals on Jewish festivals, each preceded by kiddush, one in the evening and one in the morning. For both meals for each Jewish festival day (and all three meals on Shabbat), say ha'motzi over two complete loaves of bread, each of which is at least 1.3 fl. oz. in volume. 

Source of Saying Jewish Festival Kiddush
Some kiddushes are commanded by the Torah (d'oraita); the others are from Chazal (d'rabanan), as follows:
Kiddush d'Oraita

• First night of Jewish festivals
• Night of seventh day of Passover
• Night of Shmini Atzeret.

Kiddush d'Rabanan

• First day of Jewish festival
• Second night of Jewish festival
• Second day of Jewish festival
• Seventh day of Passover
• Eighth night of Passover
• Eighth day of Passover
• Shmini Atzeret day
• Night and day of Simchat Torah.

Source of Jewish Festival Kiddush Location
Saying Jewish festival kiddush at the place where you will eat your meal is a rabbinical (d'rabanan) enactment.
Jewish Festival Kiddush-Meal Quantities: Evening

• For evening kiddush for a first-night (d'oraita) Jewish festival, a minimum of 4 fl. oz. (119 ml) of wine must be blessed on and at least half must be drunk.
• For evening kiddush for a second-night (d'rabanan) Jewish festival, a minimum of 3.3 fl. oz. (99 ml) of wine must be blessed on and at least 2.0 fl. oz. must be drunk.
• For the evening meal, as on the first two Shabbat meals and for all required Jewish festival meals, a minimum of 1.9 fl. oz. (56 ml) of bread must be eaten within four minutes.

Eating Requirements for Jewish Festival Morning Kiddush
There are two separate eating requirements during the daytime. They may be combined (say/hear kiddush and start the main meal right away) but are often done separately (say/hear kiddush and then eat some light foods and beverages; the main meal is eaten later in the day).
Note Since eating and drinking requirements on all morning kiddushes (both Shabbat and Jewish festivals) are d'rabanan, the required beverage amount for morning kiddush is only 3.3 fl. oz. (99 ml) instead of the d'oraita 4 fl. oz. (119 ml) (which is required for kiddushes for Shabbat evening and all first-night Jewish festivals).

• Morning kiddush requires a halachically legal “meal” with these elements:
  • Blessing on a minimum of 3.3 fl. oz. (99 ml) of wine (or other beverage),
  • Someone's drinking at least half the beverage, followed by
  • Eating at least 1.3 fl. oz. (39 ml, or 1/6 cup) of some type of mezonot within four minutes. 
    Note If you drink at least 3.3 fl. oz. (99 ml) of wine within 30 seconds, you do not need to eat mezonot.
    Note You do not need to drink the wine or other kiddush beverage to fulfill “establishing a meal.” You may hear kiddush and then simply eat the required amount of bread or mezonot. This applies to Shabbat or Jewish festivals, evening or morning.
     

 

• The real meal (kovei'a se'uda) requires eating at least 1.9 fl. oz. (56 ml) of bread (or matza during Passover!) within four minutes. It must include enough food to satiate. 
  Note You can simultaneously fulfill the requirement to “establish a meal” and to “eat a meal” by eating one (the same) piece of bread.

Don't say ha'gomel for anyone other than yourself (not even for your spouse or children). Likewise, one person may not exempt the entire congregation for ha'gomel except b'di'avad.  But when an entire congregation says ha'gomel, use “gemalanu.”

Human life is valued in Judaism, unlike in some other religions. The Talmud says that if someone saves one human life (pikuach nefesh), it is as if he or she saved an entire universe. Almost all halachot may be overridden in order to save a life; the main exceptions are for Adultery, Murder, and Idol Worship—see Adultery, Murder, Idol Worship .

How To Reheat on Hotplate or Blech: Before Shabbat Begins

1. Cover any cooking controls (knobs, switches, etc.) so no one adjusts them during Shabbat.
2. Cover the heat source with a "blech" (sheet of metal). This will help prevent Torah law violations by serving as a reminder not to adjust the heat.                                      Note Some blechs also block the temperature controls, to help with the previous step.                                                                                                                                Note To use a hotplate, remove the control knob before Shabbat.
3. Turn on the source of heat (hotplate, burner under the blech...).
4. Put onto the hotplate or blech at least one utensil containing food or water.

1. Start with food that is fully cooked and solid (no liquids may be heated on Shabbat!). Note"Solid" food includes cooked meat with congealed jelly or cooked fish with jelly.
2. Place the fully cooked dry food on top of the food- or water-containing utensil that had been placed on the heating appliance before Shabbat began. Remember not to put the fully cooked food directly onto the hotplate, blech, or other heat source after Shabbat begins (even if there is a separation between the heat source and food).

Note After sunset on Friday, you may not put any incompletely cooked food (whether hot or cold) onto the heated part of the heating appliance or move it from a cooler part of the blech to a hotter part.
NOteAt some time during Shabbat, someone must eat or drink from the food- or water-containing utensil that had been on the blech since before Shabbat began.

You may not turn off or disconnect an operating electrical device (such as an alarm, appliance, light, oven, or any machinery) on Shabbat, even using a shinui and even if the noise will prevent you from sleeping. You may ask a non-Jew to turn it off, but you may not ask a Jew, not even a child below bar/bat mitzva age.

L'chatchila, you should not bake uncovered dairy and meat foods in the same oven at the same time, even if both pans:

• Are non-liquid, AND
• Do not touch each other.

B'di'avad, both uncovered pans remain kosher—even if they touch each other, if both pans:

• Are non-liquid,
• Are clean and dry (on the outside), AND
• Do not contain spicy/charif food.

When a person speaks directly to God, it is very important to demonstrate humility. Since the Talmud says that covering one's head is a form of humility (and that learned Jews/talmidei chachamim used to cover their heads), men who wear a talit for prayer should ideally use it to cover their heads whenever they wear it, but the minimum is during the amida.

To dispose of items used for mitzvot (tashmishei mitzva) such as tzitzit or etrog, you may wrap in one layer of plastic and throw it into dry garbage, or wrap in two layers of plastic and throw it into wet garbage.

On Shabbat, you may not carry items in a building (such as a condominium) owned by more than one Jew (even if the other owners are not religious), from a condo into the hallway or from the hallway into a condo unless:

• There is an eruv around the building, or
• You have made an eruv chatzeirot with all the other owners.