Mobile phone and mobile internet is now the best way of getting around the islands, particularly Sal. The problem is that to use your mobile from abroad, you may very well spend a fortune phoning home. If you use Facebook messenger, Viber, Skype or Whatsapp, then see if this solution will work for you.
When you get off the plane, leave the 'flight mode' on and 'data roaming' off. Go to a local phone shop and get a local SIM card with data (you must take the mobile phone you will be using with you as the shops will set up your new SIM card, activate and then put your data on the phone for you). The cost at the time of writing (Jan 2018) is about 12.5 Euros for 5GB of data. Better still, bring a spare mobile phone with you and the phone shop will put the SIM in that, provided the phone is unlocked to any network. Then, set the phone to 'mobile hotspot and tethering' (share the internet) so you can use your wifi on the move. More instructions below in the youtube video. Basically, you are using the spare mobile phone as a mobile router. You can usually log up to 5 of your other devices to the one 'internet' phone such as laptops, tablets and kindles.
If you go into a big hotel or bar, then you can also use their wifi, but using your own phone internet is far more secure, and, in most cases competitive for price.
In Santa Maria, only one of the mobile phone shops can sell the SIM for CV Movel, but two more can do the 'top ups'. Below is a map showing the SIM card shop.
Click on the images with three words on them to view an exact location where the image was taken using what3words app
mobile phone tethering
mobile phone and internet