The bus is defenitly the best way to go. Just take bus 19 from the airport and you'll end up at Alameda principal or Paseo de parque. These two streets are the two main bus streets where all the buses goes from. Every bus stop has a map that shows where the bus goes.

A single ticket costs 1:10€

A ride as much as you want during one month card costs: 34€

Then you also have a card that you can refill and the monthly card is cheaper for students.

The place where you buy your card is located on Alameda principal, it is across the street from calle Larios (which is the shopping street) and just follow Alameda principal and you'll find it.

To get around the center of Malaga, it is easiest to walk and there's a beach walk that is really nice to.

I hope that answers your question :) and if it doesn't, just ask me again!