If she plucks, do not attend to it. Give her lots of time out of her cage. Engage her with foraging and toys and make sure you have her checked by a CAV (Certified Avian Vet) to rule out anything like PDD that might cause plucking.
Try to pay attention to when she plucks and see if you can distract her without paying overt attention to the behavior. Also, based on when she plucks, (or over-preens) look for patterns and try to avoid or desensitize her to those situations. When she isn't plucking/over-preening, pile on the attention (assuming she likes you lol). Try preening rings, foot toys, mop heads (if bird safe) etc in order to foster replacement behaviors.
Make sure she isn't nervous or bored and make sure that she isn't being hormonal. Hormonal birds will sometimes pluck, so avoid warm foods, dark spaces of any kind and "cuddling" (stick to petting on the head).
Pay attention to diet and humidity. Sometimes deficient birds will pluck or over-preen, so make sure your bird has up to date medical records and that there are quality pellets +veg involved daily. Sodium and preservatives can increase plucking behavior.
In terms of humidity, look up your species and determine what is normal in their native habitat. Dry skin can cause plucking, but excessive bathing can cause hormonal behavior, so a balance is needed. Get a humidity gauge and monitor levels---if you use a humidifier, make sure it is PFOA/PTFE free (no teflon or fluoroplastics) and use distilled water or the upper portion of tap water that has sat out for a period of time (minerals in regular water are harmful to bird lungs).
Last but not least, be cautious of environmental allergens and irritants. Perfume, cologne, lotion, scented cleaners, candles, air fresheners, nail polish etc can all irritate bird's lungs and skin....as can other pets in certain cases. If your bird is very dusty, consider an air purifier, but make sure it is a non-ionizing/non-ozone producing one!
As a last resort, there are medications that may help with OCD etc. There are also homeopathic and natural treatments that have been reportedly used with mixed success.