Visit the official Balearic Islands and Mallorca tourism board website for a good overview of the island. Learning about its culture, geography, highlights and attractions will help immeasurably as you plan the general logistics of your trip. From here, visit or read a guidebook about the island that includes what it takes to get there and what to expect when you arrive.
Visit one of the many online villa and apartment rental brokers who represent property owners and add a fee to the transaction when you rent. Most of the more luxurious and historic properties will be rented via one of these brokers, as their owners don't wish to take part in the process. Select something in your price range that places you in the location you want for the number of people in your party. A wide array of amenities will be available, so make sure to keep an eye out for whatever's most important to you, be it a swimming pool or an Internet connection.
Visit the growing number of by-owner online villa and apartment rental services online. These services, which provide an outlet for renters to reach their potential audience directly, either charge a small fee or make due with advertising much like a CraigsList. The result is cheaper accommodations for the most part and direct dealings with the property owners. These villas and apartments are often not of the glamorous variety, but are quite nice and reliable.
Pay the property deposit using PayPal or some other escrow service. If using a broker, you may have to follow the company policy and pay the full amount upfront. Research your preferred rental company to make sure it's reputable prior to paying. If you're dealing with a private owner, insist on paying only the deposit upfront, with the rest due upon arrival in cash. You won't risk losing your money, can inspect the property prior to paying and will avoid taxes this way. If you must pay in advance, use a major credit card so you can dispute the charges should anything awry occur.
Arrange for your property owner to meet you at a place of your choosing, which will likely be a port, landmark or the villa itself. This person will have you sign a release, collect your rent and hand over the keys. Passport copies and a list of all occupants will be made. With this formality out of the way, the villa is yours. If you've rented through a broker, expect to meet the representative in much the same way and for the same reasons. Many brokers can also arrange for your airport or ferry transfer for a fee.