Countries have different standards, so when moving abroad becomes imperative to have a basic knowledge of the standards used locally. Paguro has already done the research for you.

Language: official language is Spanish, but many other native idiomes are spoken by minorities like various Mayan, Nahuatl, and other regional indigenous languages. English is spoken as a second language by a growing number of people and is becoming a necessity for any professional or enterpreneur.

Religion: the prevailing religion is catholic, but there isn't a state religion and freedom of cult is acknowledged. There are temples of all types along the territory, mainly in the capital and principal cities. Protestantism as well as Judaism and many other existing religions are practiced. Mexico does not have a history of religious prejudices.

Currency: the Mexican currency is the peso, which consists of:

• Coins of 20 - 10 - 5 - 2 - 1 pesos, and sub-units of 50 and 10 centavos. Click here if you wish to see the images of the mexican coins.
• Banknotes of  20 - 50 - 100 - 200 - 500 pesos. Click here if you wish to see the images of the mexican banknotes.

It is best to exchange currency at the booths in the airport, where competitive exchange rates are offered. Outside the airport, go to a large bank branch. You may exchange money at hotels, but they usually charge high commissions or have very unfavorable exchange rates. Most department stores and restaurants will accept US dollars, but you would get a better exchange rate at a bank or reputable exchange house.
To see the most current rates, you can use one of the many available currency conversion tools available on the internet, find two useful links below.
website: www.oanda.com/convert/classic
website: www.xe.com/ucc

Time zone: Mexico states fall in three time zones as indicated below, even though most of the country is within the Central Standard Time zone:

• The Mexico states of Nayarit, Sonora, Sinaloa and Baja California Sur use Mountain Standard Time (GMT -7h, meaning you have to subtract 7 hours to Greenwich Mean Time, so if in London is 12 o' clock, in Sonora is 5 a.m.).
• Baja California Norte uses Pacific Standard Time (GMT -8h, subtract 8 hours from Greenwich Mean Time).
• all the other states, which includes most of the country, uses Central Standard Time (GMT -6h, subtract 6 hours from Greenwich Mean Time).

Mexico, with the exception of the State of Sonora, observes Daylight Saving Time which starts at 2:00 a.m. local time on the first Sunday in April and returns to Standard Time on the last Sunday in October at 2:00 a.m. The names in each time zone change accordingly with Daylight Saving Time, so Central Standard Time (CST) becomes Central Daylight Time (CDT), etc.

Electricity: In Mexico the voltage is 110 volts (100-127V), 60 hertz. It is important to pay attention to the voltage system. Even though you've bought a plug adaptor, the different voltage may cause your expensive electrical appliances to stop working with a bang in a smelly cloud of blue smoke. Check with your landlord. Many houses in Mexico have a 2nd entry for 220 Volts. If available you can ask an electrician to make a connection where you need it. Luz y Fuerza del Centro is the name of the government-owned company that supplies electricity in Mexico.
If you occupy a new house or apartment, you will need to set up an account with them at one of their many offices. If your residence has been occupied before, you won't need to set up such an account. You will receive the bill either monthly or every two months, which you may pay at any branch of the banks listed on the bank of your electricity statement. For additional info, you may visit their website and click on the FAQ (Frequently Asked Questions) link.
website: www.lfc.gob.mx

Electrical plugs: Type A, an ungrounded plug with two flat parallel prongs which is found in most of North and Central America. Plugs for appliances consist of twin flat parallel bars, very similar to the plugs in the United States, but in the US plugs, one bar is slightly wider than the other one.
In typical wall outlets, both slots have the same width, so an American plug won't fit in. You will find that in some houses, the wall outlets have been adapted to receive an American plug (one slot is wider than the other). In this case, you may connect either an American or a Mexican appliance there.

Phone jacks:  The phone jack is the RJ11, the same in use in the United States. The phone lines are digital.

Mobile phone: GSM is the standard for mobile phones in Mexico. If you have a tri-band mobile phone, you can use it in Mexico. Note: most likely you will not be able to send SMS abroad from your mobile phone (inside Mexico it is possible), unless you sign a contract with the local company Telmex, renewable monthly. To sign a contract you need a valid ID plus a proof of residency (water bill, telephone bill...).
To call a mobile phone from a land line within Mexico dial: 044 + city code + mobile number.
If you call from a mobile phone to a mobile phone, omit 044 + city code and dial the number only.
To reach a Mexican mobile phone from abroad, you need to omit the 044, and dial as if it were a land line telephone number, complete with country code and area code.

TV system: NTSC.

DVD zone: DVDs are Region 4 (included in region 4 are besides Mexico, South America, Central America, Australia, New Zealand, Pacific Islands, Caribbean).

Measure system: Metric, unite measure of weight is grams.

Phone code: The country code for Mexico is 52
International phone calls

• Calling Mexico: IDD of the country you are calling from + 52 + area/city code + phone number
• Calling from Mexico: dial 00 before the country code+area/city code+phone number.

Paper : Mexico (even though some changes are taking place), as well as United States and Canada, are today the only industrialized nations in which the ISO standard paper sizes are not yet widely used. The paper formats used are:

"Letter" (tamaño carta)     279.4 cm x 215.9 cm (11 in x 8.5 in)
"Legal"  (tamaño oficio)    355.6 cm x 215.9 cm (14 in x 8.5 in)
“Executive” (190 × 254 mm)
“Ledger/Tabloid” (279 × 432 mm)

Mattress sizes: 
Individual   100 x 190 cms. (39 x 75 inches)
Matrimonial  135 x 190 cms. (53 x 75 inches)
Queen Size   150 x 190 cms. (59 x 75 inches)
King Size    200 x 190 cms.  (79 x 75 inches)
Cuna (crib)  71 x 132 cms.   (28 x 52 inches)

Pillows and Bed linens: When buying linens, the fitted sheet will usually be measured according to the mentioned mattress sizes (top surface of the mattress). The flat sheets will usually measure from 40 to 60 cm more than the top surface of the mattress.
Note that mattress depths vary widely by manufacturer. Measure the depth of your mattress before purchasing sheets or ask in the store whether exchanges are possible BEFORE paying.
Pillows standard is 51 x 66 cms. (20 x 26 inches), but in department stores like Liverpool, Palacio de Hierro, and Sears, it is very possible to find pillowcases in King, European, and Square sizes, just ask!

Tableclothes or table linens: Always measure the maximum length and the maximum width of your table. Decide how long you want the cloth to drop down from the table, this drop lenght is called the drape and is normally 20 to 30 cm.
Determine the table cloth size by adding twice the drape to the length and width you got when you measured table length and width.
Example: If your table is 110 by 180 cm and you want the drape to be 20 cm, add twice the drape (20+20 = 40 cm) to both the table length and table width to get the table cloth size.
Your table cloth size will be 150 cm (110+40) by 220 cm (180+40).
If the store does not have the measure you are looking for, ask if or where you can have them custom made, which is very possible at some department stores or linen stores.

Clothing sizes: Unfortunately, there isn't a standard for sizes! In recent years, American sizes have become more common in Mexico, specially at department stores.
However, it is also common to find clothes in the European sizes.
More informal clothes, like T-shirts and leggings, come in sizes XS, S, M, L, XL.
Children's clothes are usually related to the child's age, meaning that a 10 size usually fits a 10 year-old child.
Always keep the sales receipt in anything you purchase, in case you need to exchange your purchase.

Women's dresses
European size is 28-30 more than U.S.
Example: US 6 = Euro 36

Women's suits (formal)
US use dress size
European size is 28 more than US
Example: US 6 = Europe 34

Men's suits and coats
European sizes are 10 more than US
Example: US 36 = Europe 46

Shoes

Women's Shoes
Mexico  US       UK             Europe    Japan
2           4      2 and 1/2      35          21.5
3           5      3 and 1/2      37          22.5
4           6      4 and 1/2      38          23.5
5           7      5 and 1/2      39          24.5
6           8      6 and 1/2      40          (rare)
7           9      7 and 1/2      42          (rare)

and there are half sizes in Mexico: 2 1/2, 5 1/2, etc.

Men's Shoes
Mexico  US         UK            Europe      Japan
5            7      5 and 1/2      39            24.5
6            8      6 and 1/2      41            25.5
7            9      7 and 1/2      42            26.5
8          10      8 and 1/2      43            27.5
9          11      9 and 1/2      45            (rare)
10        12     10 and 1/2      46            (rare)
11        13     11 and 1/2      47            (rare)

and there are half sizes in Mexico: 2 1/2, 5 1/2, etc.