As for actually travelling on your own is concerned.... Don't be too worried about it. I travel alone most of the time and it's nice to arrange things for yourself and not have to worry about what others are always wanting to do. You'll meet people en-route for sure, especially if you're on a train for any length of time. Trains in Eastern Europe take ages to get anywhere - and never travel in a straight line!!
One example is the journey from Sofia to Dobrich. Look at the map of Bulgaria, look at the two cities and then where Ruse (on The River Danube) is. One of the trains from Sofia to Dobrich goes via Ruse!! You'll meet people, don't worry.
Have a great trip.
[ Edit: Edited on 06-May-2009, at 03:15 by Redpaddy ]