To try and avoid as many problems as possible, we thoroughly researched each hostel or hotel, the area, where the attractions were and the metro stations and read all the reviews. Reviews were difficult because there was such a variety of opinions so we went with the majority. We were very fortunate that in all of the places we stayed, they were all decent, fitting most of our criteria. There were some that were better than others but we considered ourselves lucky in the ones we chose. And only once did we end up with a man in our room but this was taken care of quickly and with no problems.
There is also some stress in determining what your travel options will be. When we went to Europe, we travelled within the cities either by metro or by walking. We did an awful lot of walking. Between cities we travelled by Euro Rail except between Paris and Switzerland, we travelled by the TGV railway system which was much quicker. Trying to decide which Euro Rail passes to get was difficult too, i.e.: how many days would we need, how many stops were we going to make, how many countries would we be stopping in, etc. And then after those decisions had been made, it was necessary to determine the time schedules for each and on what track or level they were leaving.
After those decisions had been made, we had to decide what attractions were important to see and on what days, depending on our arrival and departure times, and in what order so as to be able to see as much as possible. We knew we wouldn't have time to see everything and there were three people who may have had differing views. In this respect we were in agreement with what we all wanted to see.
There is stress, to some degree, even when travelling with a tour group. What are the people going to be like? Is there going to be anyone who is difficult, are they going to be friendly and inclusive? And if you are sharing a room, what will your roommate be like? What is the tour guide going to be like? Is the trip going to be as enjoyable as you thought it would be? Are you going to see all that you expected to see?
There is no way to completely avoid stress altogether either before, or while you are travelling. But some suggestions are to read reviews avidly, know as much about the area you are visiting before you go as possible, and best of all is to have word-of-mouth recommendations from someone you know and respect.
But once all the decisions have been made, hop on board and enjoy your next adventure.