First of all, I need to check all the maps and guides online about the places I want to visit. This applies even to areas nearby, because I'm super meticulous about that. Then I look for places to stay, people usually stay at hostels or hotels but I prefer to rent an apartment. Here's an example from my last trip to Varna, Bulgaria. I was traveling with my sister and was looking for a Bulgarian property for sale Varna Suprimmo.net where we two could stay for a week or two, and gladly we found it.
Only after that, I can book tickets and finally pack my travel bag.

You can't be prepared for everything, which doesn't mean you shouldn't get prepared at all, that's my motto about traveling.