Kabbalat Shabbat is mostly omitted when Shabbat falls on:

• Jewish festivals,
• Chol ha'moed, and
• Right after the last day of a Jewish festival. 

On these days, only Mizmor shir... and Adonai malach... are said.
 

There are many approaches as to when to start Shabbat:

Men
For men, whichever is first:

• At sunset, or
• When they light candles intending to begin Shabbat then, or
• When they say Mizmor shir l'yom haShabbat.

Women
For women, whichever is first:

• When they light candles intending to begin Shabbat then (most people light 18 minutes before sunset but local customs can vary; e.g., Jerusalem), or
• In case of urgent need, just before sunset if they have not lit candles.

 
Note Even if a husband has finished ma'ariv for Shabbat, his wife is not required to start Shabbat when he does, and she may still light her candles at the normal candle lighting time. The husband does not need to wait outside until she has lit. However, the ideal situation is for the home to be ready (including table set) by the time the husband has finished ma'ariv and has returned home from synagogue.
 
Community-Wide Considerations

• If an entire community begins Shabbat at any time earlier than sunset on Friday, EVERYONE must begin Shabbat at that time.
   
• If there are at least two minyans in any community, no one is required to start Shabbat with the earliest one (but if you associate yourself with one of those minyans, you must follow their custom).

If you are outside techum Shabbat (which may be as little as 0.7 miles, or 1 km, past the last house of an inhabited area—city, village, etc.), you may start Shabbat at sunset even if the nearby community starts early, as long as the rabbi from that community does not have authority over your area.
 

If an entire community starts Shabbat early, individuals must also start early.

Don't pick up the lulav or say the blessing on Shabbat.

For HaMotzi on Shabbat, see Shabbat: Two Loaves (Lechem Mishneh).

Selecting Good from Bad and Bad from Good
Boreir Principle #1: You may eat anything in the manner in which it is normally eaten.
ExamplePeeling an orange.
 
Boreir Principle #2: You may not use a specialized tool.
 
Boreir Principle #3: You may not remove “bad” from “good.”
What To Do  Take good (edible or desired food) from the undesired (bad) components.
Note You may do this only when you are ready to eat it or when you are preparing the food to be eaten soon afterward.
 
Note Boreir is a complicated area of halacha. Because issues of boreir are almost always from the Torah (d'oraita, not d'rabanan), we are stringent in applying restrictions concerning boreir. Consult a rabbi for specific questions.
 
Selecting Undesired from Desired Food
On Shabbat, you may not usually separate totally undesired from totally desired food in a standard way, even without a specialized tool.
    NOTE As on Jewish festivals, an action needed to eat a food normally (derech achila) does not violate the prohibition of boreir on Shabbat. So you may peel a food that is normally separated from its peel or shell in order to be eaten, as long as you do not use a specialized instrument to do so. For example, on Shabbat, you may do the following by hand without a shinu'i:

• Peel an orange
• Remove the shell of a hard-boiled egg
• Separate peanuts from their shells.

NOTE If peanut shells are then put into a container that also has unshelled peanuts, you may not remove the empty shells from that mixture!
SITUATION You want remove dirt from a carrot's surface on a Shabbat.
WHAT TO DO You may remove the dirt with an altered method (shinu'i), such as scraping the peel with a knife (which is a tool not specialized for separating food)-- but not by using a peeler.
REASON The normal way to eat the carrot is to peel it.
 Selecting Desired from Undesired Food
 
While eating food (and some time before--within the amount of time you would normally need to prepare a meal), you may select desired food from undesired (or inedible) substances by hand or non-specialized tool. You may not use a specialized implement.
EXAMPLE You may remove fish from its skeleton even before eating it, but you may not remove the skeleton from the fish (because you have removed bad from good).
NOTE Once Shabbat has begun:

• You may remove fish bones from fish while you are eating the fish, but not before you are eating the fish.
• You may cut open a melon such as a cantaloupe and shake the seeds out (this is because some of the seeds remain), or take a bite of the melon and spit out the seeds. But you may not remove any remaining seeds using your hand or an implement.

EXCEPTION If you take undesired elements along with the desired food, it is not considered to be separating:  you may use a specialized tool and it does not have to be eaten soon (within the normal food-preparation time).

Here are some suggestions (these are NOT halachot!) of what to prepare in advance of Shabbat. Add or delete to suit your needs!
 
Candle Lighting

• Check candle lighting time
• Set the candles in their holders (and have matches nearby)

 
Set the Table
Set the table, including the challa and its cover and the wine cup.
 
Kitchen Preparation

• Sharpen knives
• Tear paper towels
• Refrigerator: Turn off or unscrew lights; disconnect any LEDs or fans
• Set up blech
• Set up hot water urn
• Turn off stove, oven

 
Food Preparation

• Thaw frozen meat, fish, and other food that might take hours to defrost before being cooked
• Cook whatever can be cooked ahead of time on Thursday night, Friday morning, or earlier in the week
• Squeeze lemons; do any other boreir-type preparations
• Chill wine
• Open bottles and cans that will be needed on Shabbat
• Prepare tea essence

 
Cleaning

• Make beds
• Sweep or vacuum
• Dump garbage

 
Clothing

• Do laundry
• Empty pockets of muktza (or if there is no eruv, of everything!)
• For men, set out Shabbat talit

 
Muktza
Check that nothing you will need is beneath a muktza item
 
Personal Care

• Cut hair and nails, if needed
• For men, shave or trim beard and mustache, if needed
• Tear dental floss
• Tear toilet paper or put out tissues in bathrooms
• Open any new boxes of tissues

 
Electronics

• Set heat or air conditioning
• Turn on or off lights, or set timers for them
• If desired, turn off or disconnect:

• Alarms 
• Cellphones and phones
• Computers
• Microwave detectors
• Other electronics

 
Eruv
Check that the eruv (if any) is good

Since wool and/or leather was dyed for the Tabernacle in the desert, similar actions are forbidden today on Shabbat. Any action that causes one item or substance to change its color may be forbidden, even if it is not related to dyeing wool and/or leather.

If you fly through Shabbat (permitted for business only), you must keep even Shabbat d'rabanan while flying over the area of the earth that is in Shabbat.
If you fly east (such as from Asia to the US, across the Pacific) after Shabbat is over, you will re-enter Shabbat and may not do melacha on the airplane. Say the Shabbat prayers and kiddush at the appropriate local time where you are flying.
 

Situation You are are flying for business on Friday and the flight is delayed. The flight will leave after sunset.
What To Do
You may stay on the airplaine.
Note If you are flying for pleasure, you must get off the plane before sunset (if possible).

You may leave until sunset on Friday if you are flying for business, but you must be VERY careful to avoid doing any melacha while transiting Shabbat in flight!