First of all, you should decide a particular country or destination of Europe before making contact to different travel agents.
You should also decide your route for traveling whether you want to take a plane or want to enjoy traveling in a cruise. This is the most essential aspect of a tour and you have to decide it before getting information about the tour packages.
Budget is another important aspect for a tour to Europe and your budget will help you to decide whether a plane is suitable to you or a cruise will be more beneficial.
You need to decide a schedule including on which day you will be leaving for the tour and how many days will you spend at your destination in Europe.
After deciding all these things, you should contact to different travel agents operating in your area. Contacting to different agents will help you in getting a better idea about their prices and will make it easy for you to hire the services of a particular travel agency that suits to you.
You should try to visit Europe in summer season because in most part of Europe the weather becomes pleasant during summer. In winter, a huge majority of European countries become too cold and people avoid visiting Europe during winter.
However, on Christmas, people from all over the world travel to different European countries and if you are also going near Christmas, then make sure you have booked accommodation before your arrival through your travel agent.
You should also get the services of a travel and tour agency that also offers booking of different visiting places at your destination in Europe. It will help in you in making your schedule accordingly.