Seychelles are well known as a veeery expensive holiday for the ultra rich, but not need to be.
Best flights are via Middle East – I have been deciding between Emirates and Etihad. There are great options available for accommodation ranging from guesthouses and self catering villas via mid-range hotels to those all inclusive plush resorts.
Upon arrival, you will fill in two forms. One is a health questionnaire so remember when you were last left with a headache or a sore throat. This way, the country protects itself from uncontrolled spread of contagious diseases. The second one is an immigration form, where you need to state also hotels you will stay at. The immigration officer will ask for confirmations of accommodation and departing flight.
Best means of transport on Mahe and Praslin is to rent a car. Prices are often quoted in Euros. Careful, driving is in the left. The taxis are also available, but public buses are quite reliable and cost only 5 rupees per ride.
More detailed info is in my slovak article.