The Seychelles are not tolerant of backpackers turning up at the airport without accommodation booked. In such a situation, you will likely be taken to a counter where you will have to book & pay for accommodation for the duration of your trip before being allowed through immigration. Visitors need to provide details of their accommodation on their landing card Hotel Name, address, phone number, and additionally, being questioned by the immigration officer about their accommodation details "Is your booking at hotel
Most accommodations are relatively expensive and some islands have only one hotel. In fact, some of the islands aren't even permanently inhabited and accommodation can be found on fewer than 10. Your best bet for a budget bed is renting an apartment or bungalow, which are available at better rates. Also keep in mind that hotel prices greatly increase and accommodation can be hard to find during the peak seasons from December to January and July to August. Holidays such as Easter can also get very busy.
Most resorts can be found on the main islands of Mahe and Praslin. A few very high end ones, like the North Island, have their own private islands. Additionally, you will find an array of 'small hotels' which can be ideal as a get-together venue with that special feeling of exclusiveness.