Most nationalities can enter Singapore without a visa. Refer to the Immigration and Checkpoints Authority [6] for current guidelines, including a list of the 30+ nationalities that are required to obtain a visa in advance. Entry permit duration (in most cases either 14 or 30 days) depends on nationality and entry point.

Singapore has very strict drug laws, and drug trafficking carries a mandatory death penalty — which is also applied to foreigners. In addition, bringing in explosives and firearms without a permit is also a capital offence in Singapore. As always, travellers should take care with their baggage and secure it appropriately. The paranoid might also like to note that in Singapore, it is an offense even to have any drug metabolites in your system, even if they were consumed outside Singapore. Hippie types may expect a little extra attention from Customs, but getting a shave and a haircut is no longer a condition for entry.

Duty free allowances for alcohol are 1L of spirits, 1L of wine and 1L of beer per person. Alcohol may not be brought in by persons under the age of 18. Note that cigarettes cannot be brought in duty free. One opened packet (not carton!) is acceptable, but anything more will be taxed. Foreigners can opt to pay the tax or let the customs officers keep the cigarettes until the next departure; locals get to choose between paying or witnessing the cigarettes being destroyed. Note that bringing in chewing gum is illegal, though customs officers would usually not bother with a few sticks for personal consumption as long as you are discreet about it.

Publications by the Jehovah’s Witnesses and the Unification Church may not be imported to Singapore. Pornography and pirated goods are also illegal.

Please note the following list of banned activities and items:

- Overhead wires
- Satellite dishes
- Standing water
- Freestanding billboards
- Malaysian newspapers
- Feeding pigeons or monkeys
- Homosexual activity

Source: WikiTravel.com