I'm 17 years old, Australian, and would like to book a return flight to Singapore with Tiger Airlines. Will I need written consent from a guardian to get on the flight or will I be ok? Thank you.
Not sure if this is any help, but with most airlines after you are 16 you are fine to travel alone (Im flying with Singapore Airlines, am 17 and didn't need written consent).

Who is going to pay for the fare, that is first.
You will also need a passport. The main point to consider too is departing Australia.
Tiger will ask for your passport even before you get to immigration.
I am over 18, so, tell me to shut up and not get involved with something I know nothing about.
Tiger will probabally ask you for that piece of paperwork.
Plus, where are you going to stay in Singapore? A lot of places will need you to make a booking. Even backpackers will need booking, and they do stipulate that you need an adult to be with you if you are under 18.
Singapore ICA might also want to see proof that you are ok to enter the country. On your flight, you will be given a Singapore embarkation card, you have to fill that in, listing where you are going to stay, etc. And check ins to hostels/hotels in Singapore, you need to show passport too.
Was it you asking a while back.
Seriously, wait till you are 18. Then you can get a Visa Debit card, make hostel bookings, travel without restrictions.
Eventhough you are close to 18, you are not an adult, esp in Singapore. If you get into some sort of grief, rare I must say, but if, whats going to happen then?
Anyway, to each their own.
You can always try to make the booking on the Tiger website and see what happens.
Or, inapt for me to say this, get your parent/s to make a booking for you at a travel agency, and sign that its ok for you to travel to Singapore, that will solve some of the problems.
Singapore while 99 to 99.9% safe, does have a small element of kids who go out looking for trouble. Even just looking at a group, for longer than a few secs can cause trouble.

According to their Conditiions of Carriage you will need a letter each time you board.
Ring their Australian phone number and ask, but good luck getting through, their phone service in Aus is hopeless.

Haha I know I'll need a passport, daycat. ; )
I didn't realise I wouldn't be able to stay at a hostel alone if I'm not 18 or that I'd have to book ahead. I'll only be staying for a few days then heading onto Malaysia.
I can't wait until I'm 18. Would it be ok if I knew someone who lives in Singapore who I could stay with?
Thanks for that Villian, I couldn't find anything on the site myself. My parents are overseas at the moment so does that make my older brother who I'm living with my "official" guardian?
Will I need letters for traveling between Singapore and Malaysia or Singapore and Indonesia too?
Thanks for the replies.

Are you sure you have to book ahead? Can someone give me a link to somewhere explaining this?

Mate, you're getting into a legal and diplomatic minefield here.
You will have to find out the requirements of the immigration departments of all the countries you plan to enter, ie Singapore, Malaysia, Indonesia as well as Australian immigration - they may not even let you leave the country. And you are going to have to carry a considerable amount of money or have access to it, to be able to support yourself for the length of your stay.
I can't imagine they will all just let an unaccompanied minor enter without an adult to meet them.
Better do as daycat suggested and put it back until you turn 18, that way you can save up some more money and not have any of these "underage" problems.

Yeah I'll have to have more of a look into this being a minor stuff. I didn't think it'd be a big deal but Singapore is a strict country. I know people who've been to Bali by themselves when they were 17 so I'll get some info from them.
I'm not a student so I don't have any problems with money.
daycat wrote I am over 18, so, tell me to shut up and not get involved with something I know nothing about.
True, daycat you were over 18 some thirty years ago, things have changed since you done your first Taliban turban and robes.
If you can buy the airticket you can fly. You would be a little out of place as an unaccompanied minor. Holding the hands of a pretty stewardess could be fun at 17. BUT get a letter from mum and dad just in case
Good luck.