If you are used to independent travelling, book your own flights/accommodation/car and have a good look round the area yourself instead of going on an organised trip
Prior to your visit think about the type of property you wish to purchase. Do you want to be part of a complex or somewhere more remote? If it's an apartment which floor would you prefer to be on? How many bedrooms do you require, how many bathrooms? Is the property going to be a holiday home or are you going to rent it out as well?
Research the extra taxes to be paid on the property. Each country has different taxes. Remember to build this into the price.
If you are hoping to rent out the property do not rely on rental to make your mortgage payments. Rental income should be treated as a bonus not a necessity.
It's easy to get carried away when looking round property, stick to your budget, remember you will need extra money for solicitor fees, furniture etc
When you have found a development you are interested in, look carefully at the plots available. Remember to consider things like when will the sun be on the terrace? Is there a road nearby? Could building work in the future jeopardise your views?
If you hope to get some rental, is it going to appeal to potential renters? Is it nearby to restaurants, etc, is it near to the beach, is there a pool for guests to use?
Visit nearby restaurants and shops, speak to the locals, ask them questions regarding the locality.
Have a look on the internet for forums for the area you are considering buying in, you might pick up some very helpful information
Get an independent English speaking solicitor. Do not go to the solicitor recommended by the developer. Ask around, word of mouth is the best recommendation.