First of all, avoid traveling in the summer. Crowds and prices skyrocket then. May. Low season is traditionally counted from the first of November until the end of March, with dramatic increases at Christmas. As for deals, there are consolidators and Web services, but Schukar still recommends a travel agent. She has stories of friends who called her to repair their disastrous purchases on the Web, where they accidentally bought two or three tickets instead of just one.
People get really confused.
Consolidators can be good. So can working with the airlines themselves. But I don't know. We look for that here, whereas an airline agent might just quote you the lowest fare without doing all that searching around. It's lovely at that time of year, and all the Christmas markets are ready and open.