start by replacing the brake pads..
FWIW , I fitted very abrasive pads* and did a few steepish down hill rainy stops , and wore thru a Mavic Hard anodized Brake track ,
to the base aluminum, Then replaced the pads with a more rim friendly compound .. Kool Stop .. the braking has been fine ever since.
* In my specific case it was Magura's rim brakes .. They have Kool Stop Molding their pads , then shipped them to Germany ,
now KS has the complete product.. as does the MFG..
I assume you have a road brake.. there are rather abrasive pad inserts made.. to do similar..
Last edited by fietsbob; 10-08-15 at 10:48 AM.