Use separate op-amps instead of a dual. Pay attention to temperature coefficents when selecting components, esp from different manufacturers. Use bandwidth limiting caps in the feedback loop. Use good decoupling caps (more importantly, have them). If you haven't, consider the use of trimpots / caps to get the best possible tracking between the channels. Don't overdo the PSU.
There is a fair bit of difference between CMOY's, yours seems to be a fairly basic one.
What do you mean with not overdoing the PSU? Don't complicate it, don't oversize it or both?