It is a non-binding custom to braid challa as a reminder of the 12 showbreads (lechem ha'panim) in the Temple that were changed each Shabbat. Proper practice is to braid each challa from six pieces of dough, as there were two columns of six loaves each.
Note Since these showbreads were not changed on Rosh Hashana and Jewish festivals, we may use round challot for those holidays (unless they fall on Shabbat or the holiday is Passover!).

Don't fold clothes (including a talit) on an existing crease on Shabbat.

One person per household should make an eruv tavshilin in order to allow cooking on a Jewish festival for the next day, if the next day is Shabbat.  The person sets aside something cooked and something baked and says a formula (which can be found in most siddurs).

Muktza (“set aside” in one's mind) is an item that normally has no permissible use (or no use) on Shabbat. Muktza items may not usually be moved by hand on Shabbat—even if your hand is gloved—except for certain Shabbat needs, such as you need the space or the item. However, it is ALWAYS OK to move muktza items with any other part of your body.
  Chazal instituted muktza rules to make Shabbat special by requiring that actions be done differently on Shabbat than on weekdays. The basis for the idea of muktza was when Moses/Moshe instructed the Children of Israel in the wilderness to prepare the mun for Shabbat in order to eat it on Shabbat. Chazal extended the idea to prohibit moving by hand on Shabbat anything that was not prepared in one's mind before sunset on Friday.
The several categories of muktza vary according to their purpose and their permissibility to be moved. Purpose Item whose normal purpose is forbidden to be done on Shabbat.
Permissibility To Be Moved You may move this item by hand, without using a shinu'i:

• If you need the space where it is resting, or
• For a permissible use.

• Using a hammer to open a coconut.
• Using pliers to crack open nuts.
• Using a portable radiator to prop open a window.

No prior preparation or thought before Shabbat is required.
Note You may not move it just to protect the item.

Muktza Machmat Gufo: No Use
Purpose An item that has no use. This item is not normally ever designated for use; for example, a rock or stone. However, an item in this “no use” category is rendered non-muktza and usable on Shabbat as long as you had intended--before Shabbat or the festival began--to use it for a permitted purpose. As long as you intended that, you do not even need to use a shinu'i. If you did not intend, before sunset on Friday, to use this normally unusable item, then you may only move it using a shinu'i.
Permissibility To Be Moved Unless you prepared before Shabbat to use it for some permitted purpose on Shabbat, you may not move it by hand even for a permitted use and not even in order to use the space where it is resting.
Note You might need to use the item regularly for the non-standard purpose because for just a one-time use, it might not be permitted. Consult a rabbi.
Exception Garbage has no use. You may move garbage within your house (example: push the garbage across the room with your foot), but if you want to dump your garbage outside and you have a private domain or an eruv, you may pick it up and carry it outside.

Muktza Machmat Chisaron Kis
Purpose A valuable item that you are concerned may be damaged.
Examples Passport, porcelain china, or other expensive and fragile or difficult-to-replace objects.
Such an item may not be moved except for its designated purpose and you may not move it once you have finished using it. But once you are already holding it, you may take it to a place where you want to leave it and you do not need to drop it where it is when you finish with it.  

Basis L'Davar Ha'Asur

Purpose Muktza item resting on a normally permitted item makes the lower item muktza too.
Example A candlestick will render the table on which it stands muktza (unless there are one or more other items that are more valuable than the muktza item, in which case the table does not become muktza).
Situation There are multiple objects; some are permitted and some are not—for example, in a drawer.
What To Do If the permissible objects are more valuable than the non-permitted objects, you may open the drawer.

Non-Muktza on Top of Muktza
If you want a non-muktza item that was left on top of a muktza item from before Shabbat started, you may use it without restriction.

 

Situation

You discover you have coins in non-patch pockets of your pants that you will wear on Shabbat.

What To Do

You may empty coins out of non-patch pockets if you need to use the pants, but not by taking the coins out: you must dump them out of the pockets.
Note If you have coins in a patch pocket, the whole garment is muktza, unless you forgot that the coins were there or if you intended to remove the coins before Shabbat began but forgot to remove them (in which case you may shake the coins out of the pocket and the garment is not muktza).

Non-Patch Pockets

Situations

Pants with muktza items in the pockets are on your bed and you want to sleep on Shabbat afternoon.

What To Do

You may move the pants off your bed using any body part including your hands; no shinu'i needed.

Item that Becomes Muktza
If you are holding a permissible item and it becomes muktza, you may put it in safe place; you do not need to immediately drop it or put it down where you are.
Example You are holding a pot from which you dispense all of the food. The empty pot is now muktza, but you may take it to the kitchen to put it down.

For More Information about Muktza

To see the TorahTots article on muktza, click here.

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.

As on Shabbat, the minimum total volume of Jewish festival kiddush beverage that must be drunk--usually by the kiddush-maker (mevareich) but it may even be several people combined--is a cheekful (m'lo lugmov)—considered to be 2 fl. oz. (59 ml) within 30 seconds.

As on Shabbat, light Jewish festival candles wherever you will eat dinner that night.

On Friday of Chanuka, light Shabbat candles after Chanuka candles; at least one Chanuka candle must burn until at least 30 minutes after dark.
If a man forgets to light the Chanuka candles, he may still light them until sunset or until he says Mizmor shir l'yom haShabbat, whichever comes earlier. 
But women start Shabbat when they light the Shabbat candles and so they may not light Chanuka candles after lighting Shabbat candles.
 

You may use one or two hands when giving a blessing, such as when blessing children on Shabbat or Jewish festivals. You may hold your hands over the person's head or actually put your hands on their head--either is OK.

If there is not enough wine or grape juice for Shabbat (or Jewish festival kiddush) and havdala:

• Set aside the first cup for havdala; then, if there is one more cup,
• Use it for the morning kiddush.
• See How To Do Shabbat Daytime Kiddush and How To Do Shabbat Evening Kiddush .

 

The earliest permissible time to say mincha before a Jewish festival is one-half hour after halachic midday, as with all mincha prayers including before Shabbat.

You may not wash or hang up wet laundry on Jewish festivals (or Shabbat).  The halachot for drying laundry depend on whether you use a clothesline or a dryer:
Jewish Festivals: Laundry: Clothesline
You may only take down laundry on Jewish festivals if it was dry before sunset at the start of the festival, and only if you don't:

• Transfer the laundry from one halachic domain to another (hotza'a), or
• Give the impression that the laundry had been washed on the Jewish festival (mar'it ayin).

If laundry on a clothesline is still wet at sunset before the festival, the laundry is muktza and you may not take it down or use it during the festival. This is different from the case of a dryer.
Reason On the clothes line, there is no certainty that the laundry will dry during the festival (it might rain, it might be cold or cloudy...), so the person may not have in mind that it will dry during the festival.
Jewish Festivals: Laundry: Dryer
Laundry in a dryer (even if it was wet at sunset) that was turned on before sunset beginning the Jewish festival (or Shabbat) is not muktza, even if you do not intend to wear it.  You may remove the dry laundry from the dryer on the Jewish festival as long as no light goes on.

In a halachically public area (reshut ha'rabim) with no eruv, on Shabbat you may move a stationary object up to 4 amot (6'9 1/2", or about 2 meters) from the place where you find it. If you are already transporting the object when you realize it, do whichever one of the following applies:
Situation You are walking on Shabbat in a public domain (reshut ha'rabim) that does not have an eruv and find something in your pocket.
What To Do

• If you were walking and are still walking, go back to the most recent private domain and leave the item there. (If you cannot reasonably get back to where that was, continue to your destination and drop the item inside the first private domain you reach.)
• If you have already stopped walking, drop the item where you are.
• If you had stopped walking and then resumed walking, drop the item where you are.

If there is not enough wine (or grape juice) for Jewish festival (or Shabbat) kiddush and havdala:

• Set aside the first cup for havdala.  Then, if there is one more cup,
• Use it for the morning kiddush.