Buses in Lisbon is best when you want to see the city by hopping on and off from one place to another. In Lisbon, buses are made convenient for passengers by utilizing multiple use cards which you simply have to swipe across the reader which tells whether you are ready to go with a green light; red means your card is used up and you have to buy another one. When you want to get around city you can find all information through the Carris website that includes the Elevador de Santa Justa, the Gloria/Bica/Lavara furniculars, trams, buses and metro, or if you may, you can pick up a map of the lines from a tourist office.
Riding a bus on your trip depends to which destination you are bound to go. There is a morning bus around 11 am and an overnight bus that leaves from Sete Rios bus station and goes through Setubal, stops for about 20 minutes in Faro before it heads to Seville, and this takes 7 hours trip. It will cost you 35 Euros with a need for a passport to buy the tickets since you are to cross Spain from Portugal.
There is also a bus from Lisbon Airport to Fatima. To catch a bus to Fatima the first station you go to have to be the Sete Rios Bus Station where the buses leave from 7:45 am until 7 pm every hour. The buses are usually double decker and are very nice especially when you sit on the main floor which is less congested and smoother. The fare each way will cost you 8.25 Euro and make a check when you arrive in Fatima. Before leaving for the trip to it is wiser to give yourself a search through the Web Site and use all capitals and spaces, then scroll down to Lugo Pages.
When you want to save on your way to the city center from the airport you can take your ride with an Aero Bus at only 3.50 Euro compared to a taxi that will cost you 10 Euro. This buses leave from the Oriente Train Station every 20 or 30 minutes from 7:00 in the morning until 11:00 in the afternoon passing through most of the 4 and 5 star hotels of Lisbon. Or, if you may, you can take as well Aero-bus 91 that departs every 20 minutes with tickets to cost 3.50 Euro which are valid on all public transportation lines except for metro for one day. These buses go along Avenida da Liberdade then through Restauradores Square and into Baixa. Other buses stop in Prace do Comercio for those who have to catch the boat that connects to train to Algarve, or in Cais do Sodre for a train to Estroril e Cascais, or in Rossio for a train to Sintra. If you wanted to be every where in Lisbon you got subways and buses.