I def. second the filing. Even if you just get some fine grain sand paper it works. I suggest filling the pads themselves and the rims for sure.

I'm pretty sure if you have canti mounts you could also switch to V brakes. Those seem to be pretty reliable and they don't need as much adjusting. I just got my first bike with canti's and I've had to adjust them a couple times. Depending on how old the bike is you may want to replace the brake cables. They can stretch over time.