Our best advice to you is 'bring only the bare necessities'. You can buy almost anything you might need and probably a lot cheaper than in your country.
A back pack is surely one of the most useful items and comes in very handy for the day trips, shopping sprees and walks. A 'zippable' backpack is a safe way to carry your belongings but a concealed money belt or shoulder wallet will certainly keep your money and documents safe from pickpockets.
Even though coastal temperatures are mild throughout the year, if you venture inland you may need a light sweater to keep you warm. For the Northern slopes some wet weather gear could save you from a surprise soaking.
If you are heading to the Night Clubs, Discos and finer restaurants, do take a set of smarter clothes. Beach wear and trainers will not be accepted.