If you are looking to set up a business, it may be easier to buy a business with a license and get it transferred, than to try and apply and get one for the first time. Again, some people who have tried to do this without finding out about some of the difficulties have learned the hard way. It is not an easy process, you may think you can get it sorted yourself but even with the help of Lawyers you will still find in some cases the process very frustrating. Some people are not aware of the license application and approval requirements, all which have to be presented in Portuguese on the appropriate forms to all the right people and then stamped. There may be costs for some of the documentation and license approval you won't be aware of, try and get these identified at an early stage.
Rental agreements, monthly rental costs or purchase of the right commercial/property, do your homework before signing contracts, make sure you that you have the licence or can get a licence to trade. A few places have been shut down after opening for not having the appropriate license or documents, in one situation I do know that the Lawyer had not processed the paperwork related to getting final approval to open the business for trading purposes, so make sure that your communications regarding such matters with your lawyer are clearly understood.
Some people are seeking to set up a beach business. With this you need to look into what licence you need, whether there are any restrictions, what type of building will be allowed....temporary, wooden framed, will you need a water supply, where will the water supply will come from, how will it reach the premises, does it have road access, where will the new promenade come across the beach, does a developer already have plans for the beach. The Riu Hotel uses the beach area in front of their hotel, and so do other hotels, but the beaches will remain public! There are some people who have a licence to supply and install sun umbrellas, but they also need a licence for specific areas of the beach.
You need to think about passing trade for your business. It's ok opening a Bar, but where are you going to get your trade from? How are you going to reach the people in the All Inclusive hotels who have paid for all their meals and drinks and who may not be aware of your business or more importantly can't be bothered or have the extra cash to come out to visit your business.
You may be able to work with other agencies such as Tour Operators, Rental or Sales Agencies, Hotels or Resorts. However working with some of the major hotels and resorts may require you to meet certain standards, have staff that speak a number of languages or comply to the hotel business agreement.
Go visit the island, spend some time there, speak to people and local bsiness owners before committing yourself!