Making friends is indeed difficult. I have always noticed that people who dont know each other just ignore each other, which to me makes no sense...if everybody does that then how on earth are we supposed to get to know one another? I have managed to befriend a few people, but you have to be bold and consistent. I have always had to make the first move when meeting someone for the first time. The trick seems to be that you have to make yourself identifiable with the person you are dealing with...find common ground and be lighthearted. It takes a while for a person to warm up to another person as people are naturally prejudiced and distrusting (in my opinion at least..) I think its always best to start befriending people that remind you of yourself, because chances are, you remind them of themselves...and thats always a good start...
I know what you mean though, it is indeed difficult to form friendships, and its only after quite a long period of time of being around someone and doing things together that a true friendship forms, and unfortunately for people like us...the quieter more anxious ones...its a lot more difficult.
I remember when I was younger that I had this belief that if there was enough desire...everyone could at least get along with everyone else, but I know now that the scope of human personality is too wide for that to happen
Anyway..I will shut up now.. I just thought I would share my thoughts, its a very interesting topic.
A good book you might be interested in reading is how to win friends and influence people...its old, but still a good read.