When you don't have similar interests with somebody but really want to be friends! what can you talk about?

There's always gonna be something to talk about just gotta look for it... :)

Just ask them about themselves (what are they doing this weekend, New Years, how tiring school/work is, or a simple "how was your day").

Any of the above work fine, the more you talk to people, the less "awkward" it's gonna be, and conversations will flow much much more smoother. :)

Good Luck

Girls and more girls. Other stuff comes along with time.