Initially I wanted to install a rack, but the LBS guys told me that they can't do that, because my bike was missing a couple of holes on the seat stays.
I looked on the internet and I saw that the usual solution is with P-clamps.
Then, I made a trip to the local hardware store, but they didn't have P-clamps, so I bought myself the next best thing: some L-shaped brackets, to be mounted using the hole on the seat stay bridge.