The key to good adhesion is geting the mating surfaces clean, very clean. Do that with whatever means is required, steel wool maybe, solvents like alcohol or lacquer thinner may help. Just don't get sloppy and spill solvents where they may delaminate something. Maximum adhesion in most instances is best achieved with a slow cure epoxy. A common, easily sourced one is "JB Weld." I'm fond of marine bonding epoxy adhesives, but they're harder to find.
