Entering and exiting Singapore is usually fast and efficient. You'll be issued with an embarkation card on arrival; don't loose this as you will need to surrender it on departure.
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.
Passport holders of all countries (who have secured the appropriate visa, where applicable) are able to enter Singapore. You must have at least six months validity on your passport before entering.
Citizens of most countries are granted 90-day entry on arrival. Citizens of India, Myanmar and certain other countries must obtain a visa before arriving.
Visa extensions can be applied for at the Immigration & Checkpoints Authority website.