You are not allowed to bring tobacco into Singapore unless you pay duty. You will be slapped with a hefty fine if you fail to declare and pay.
You are permitted 1L each of wine, beer and spirits duty free. Alternatively, you are allowed 2L of wine and 1L of beer, or 2L of beer and 1L of wine. You need to have been out of Singapore for more than 48 hours and to anywhere but Malaysia.
It's illegal to bring chewing gum, firecrackers, obscene or seditious material, gun-shaped cigarette lighters, endangered species or their by-products and pirated recordings or publications with you.
The visa application form is available free of charge at all Singapore overseas missions (except for non-resident High Commissioners/Ambassadors based in Singapore). The list of our Overseas Missions is available here. You can approach the nearest Mission directly for more information on the requirements and procedures to apply for a visa.
visitors to Singapore must meet
the following entry
and Entry Requirements
Valid travel document (minimum validity of 6 months at the time of departure)
Onward or return ticket (if applicable)
Entry facilities to the next destination; and
Sufficient funds to stay in Singapore and visa for entry into Singapore (if applicable)
(Quoted from http://www.mfa.gov.sg/content/mfa/consular_information/foreigners_visiting_singapore.html)