UAE is a country that welcomes a large number of visitors from around the world. All the Emirates welcome tourists of various nationalities and cultures.
However, being a Muslim country, there are certain factors to take into consideration in terms of dress code and behaviour.
Note: This is a general informative guide and it would be best to ask in advance about etiquette tips based on places you visit or stay at in the UAE
Dress code

- Residents and visitors should dress modestly, particularly in conservative areas and public places.
- Swimwear is acceptable at private beaches or around private swimming pools, but visitors should cover up elsewhere
- Cross-dressing is frowned upon and can lead to detainment by the authorities.
- Shorts and T-shirts are suitable attire in many places, although when visiting mosques, religious sites or older parts of the city, both men and women may feel more comfortable wearing loose-fitting clothes that cover shoulders, arms and legs.
- Women will usually be required to wear a headscarf when entering mosques.
- It is important to stand up for new guests and older or higher-ranking people, and men are expected to stand when a woman enters the room.
- When greeting a member of the opposite sex who is Muslim, it is important not to offer to shake hands unless they extend their hand first – both men and women (more commonly women) may prefer not to shake hands with the opposite sex due to religious reasons.
- It is customary to accept food and drink with your right hand; this is also the hand you should eat with.
- Avoid showing the soles of your feet, or pointing your foot at anyone. If you are sitting in front of an important guest, it is considered rude to cross your legs.
- If you are hosting Muslim guests, do not offer them alcoholic beverages or pork.
Gestures

- Do not beckon or point with your finger
- If you need to use a hand gesture, use the whole hand. 
- Any obscene hand gestures in public may land you in prison.
In public

- Being drunk and disorderly in public is unacceptable, and may result in a fine or worse. Drunk driving is met with zero tolerance in the UAE.
- Photography should be done with care and be sure to ask first before snapping a photo of a national or a resident of the UAE, especially if the subject is a woman. 
- Drinking in public is strictly prohibited and so is having alcohol or other illegal substances in possession at any time.
- Public displays of affection should be minimal – holding hands is acceptable but kissing and hugging in public is not.
- Noise disruptions, bad language, making obscene gestures and showing disrespect in any way to Dubai’s religion or its leaders are all forbidden and may land you in legal trouble.
Others

- Fund-raising for charity and promotion of charity or humanitarian organisations can only be done through legally approved channels after taking the requisite permissions.
- During Ramadan, non-fasting residents or visitors are expected to follow certain etiquette rules which can be seen here.
- The following are also considered illegal: use or possession of drugs, cohabitation, sex outside of marriage, having a baby out of wedlock, adultery and homosexuality. 

Source: Gulfnews