It is best to avoid traveling at all on Shabbat.

Health or Life-Threatening Condition
On Shabbat, you may not take medicine used to promote health. Whenever there is any question of a life-threatening disease or condition, you must take medicine.

There are several categories of sick people:

• Entire Body Is Affected
  Example Fever.
  Status You may take medicines for this category; pills, such as aspirin, are OK to take.
  Exception You may not smear substances on skin UNLESS the fever is life-threatening, in which case even smearing is permitted.
• Only Part of the Body Is Affected
  Status Some medicines may be used--consult a rabbi.
• Discomfort
  Status Medicine generally may not be used.

You may not wash or hang up wet laundry on Shabbat (or Jewish festivals).  The halachot for drying laundry depend on whether you use a clothesline or a dryer:

Shabbat: Laundry: Clothesline
You may take down laundry on Shabbat only if it was dry before sunset on Friday, 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 Shabbat (mar'it ayin).

If laundry on a clothesline is still wet at sunset on Friday, the laundry is muktza and you may not take it down or use it during Shabbat. This is different from the case of a dryer.
Reason On the clothesline, there is no certainty that the laundry will dry during Shabbat (it might rain, it might be cold or cloudy...), so the person cannot have in mind that it will dry during Shabbat.

Shabbat: Laundry: Dryer
Laundry in a dryer (even if it was wet at sunset) that was turned on before sunset on Friday (or Jewish festivals) is not muktza, even if you do not intend to wear it.  You may remove the dry laundry from the dryer on Shabbat as long as no light goes on.

A Shabbat belt key should be integrated into the belt, not hanging on. 

You may pulverize a cooked egg (such as a hard-boiled egg) on Shabbat but:

• You may not use a specialized utensil (you may use a fork), and
• You must eat it immediately.

You may crush or squash an avocado (such as when making guacamole) on Shabbat, but ONLY:

• Using a shinu'i (such as a spoon, knife, or spatula),
• Without using a specialized tool (such as a grinder, potato masher, or fork),
• If you eat it immediately after preparing it, and
• If you leave some pieces larger than you normally would.

 

You may not grind, grate, or even finely chop or dice food on Shabbat. You may not use a garlic press on Shabbat.
The minimum size before violating the melacha of tochein varies by the type of food. The resulting pieces must be somewhat larger than the size you would normally use in order to be permitted.

The Torah forbids cooking on Shabbat.   “Cooking” means making food edible by heating it to above 120° F (49° C).
Cooking includes:

• You may not make a soft food hard (such as cooking an egg).
• You may not make a hard food soft (such as cooking meat).
• You may not, in any manner, heat (to 120° F or above ) liquids that you will drink or foods with liquids—such as sauces and gravies--whether fully cooked or not. 

According to the Torah, you may eat food on Shabbat that had been placed on the heat source Friday afternoon but was not completely cooked by sunset.
ReasonNo action is being taken and the cooking will be completed by itself.
 
According to Torah law, food is only considered to be cooked if it has been directly heated from the heat source, such as a kettle on a fire or a pot on a flame (even if that utensil has been removed from its heat source). This is called a kli rishon.
Once you pour water from a kli rishon into a glass, the glass is a kli sheni. Some foods, such as an egg or tea, get cooked in a kli sheni (kalei bishul--easily cooked). These foods are forbidden by Torah law to be put into a hot kli sheni on Shabbat.

• You must have taken it off with the intention of replacing it, and
• You may not put the utensil down onto a surface; you must continue to hold the food (or the utensil) in your hand.
• The heat source must be covered.

Don't fast on Shabbat (except Yom Kippur!) past halachic midday:     

• If you will not finish shacharit before halachic midday, you should eat or drink earlier in the day, even before you begin shacharit—water can be sufficient for this purpose.
• If you will finish shacharit but not musaf by halachic midday:

• Finish shacharit,
• Make kiddush,
• Eat some mezonot, and then
• Return to say musaf.

Three Shabbat Meals
We are required to eat three Shabbat meals, as a rabbinic (d'rabanan) enactment to enjoy Shabbat (oneg Shabbat). The first Shabbat meal must be at night and the remaining two must be during the day (the third meal must be eaten after halachic midday). Friday night dinner and the first meal on Saturday are preceded by kiddush. For the first two Shabbat meals, say ha'motzi over two complete loaves of bread, each of which is at least 1.3 fl. oz. in volume. For the third meal, the ideal is to use two complete loaves of bread, but the requirement of eating the third meal can also be fulfilled by eating any food other than salt or water.

Source of Saying Shabbat Kiddush

• Saying kiddush on Shabbat night is a commandment from the Torah (d'oraita).
• Saying kiddush on Saturday morning is a rabbinical (d'rabanan) enactment.

Note If you did not say Friday night kiddush, you must say that version of kiddush on Shabbat morning and it is then a requirement from the Torah (d'oraita). Do not begin with va'yechulu; instead, begin with borei pri ha'gafen and say the second blessing of kiddush.

Source of Kiddush Location
Saying kiddush at the place where you will eat your meal is a rabbinical (d'rabanan) enactment.

Shabbat Kiddush-Meal Quantities: Evening

• For evening kiddush, a minimum of 4 fl. oz. (119 ml) of wine must be blessed on and at least half must be drunk.
• For the evening meal, as on Shabbat lunch and all required Jewish festival meals, a minimum of 1.9 fl. oz. of bread must be eaten within four minutes.

Shabbat Kiddush-Meal Quantities: First Meal on Saturday
Shabbat day first meal has two separate eating requirements.  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 mezonot; 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.
1) Morning kiddush requires a halachically legal “meal” with these elements:
      a) Blessing on a minimum of 3.3 fl. oz. (99 ml) of wine (or other beverage),
      b) Someone's drinking at least 2 fl. oz. of the beverage, followed by
      c) Eating at least 1.3 fl. oz. (39 ml, or 1/6 cup) of some type of mezonot (or bread) 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 kiddush “meal” does not have to satiate.
Note If you have not fulfilled the requirements for kiddush, you may not eat other foods, such as fruit or fish at a kiddush.

2) The real meal (kovei'a se'uda) of Shabbat lunch requires eating at least 1.9 fl. oz. (56 ml) of bread (or matza during Passover!) within four minutes. It should 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.
For details on fulfilling the first two meals' requirements, see Shabbat: Kiddush.

Shabbat: Eating a Meal Requirement: Third Meal
For details on fulfilling the third meal's requirements, see Shabbat: Third Meal (Se'uda Shlishit).

Kabbalat Shabbat should ideally be started before sunset, and you should ideally get to bo'i challa at about sunset time. But you may start Kabbalat Shabbat after sunset and even after dark.

Shabbat begins for women when they light the Shabbat candles or at sunset, whichever is earlier.

Techum Shabbat (Shabbat domain) is the furthest distance a Jew may walk on Shabbat. Wherever you are when you start Shabbat determines your starting point for techum Shabbat :

• City/Enclosed Area If you start Shabbat in a city or enclosed area of any type, you may walk up to 0.7 mile (1 km) beyond the border (last house) of that city or enclosed area.
• Uninhabited Area If you start Shabbat in an uninhabited place, such as a forest, you may walk only within a 0.7 mile (1 km) radius of where you started Shabbat.

Do not eat a full meal (any bread or a lot of mezonot) after halachic midday on Friday.

Set the Shabbat table with nice tableware and tablecloth.  The custom is to have the table set and have bread on the table before Shabbat starts. 
The tablecloth should cover the table during Shabbat meals, but you may remove and switch tablecloths. Even if you have a beautiful and valuable table, you should still cover it for Shabbat (and Jewish festival) meals.