Transcranial electrical stimulation (tES) is being widely investigated to understand and modulate human brain function. The interest in using tES to enhance cognitive abilities not only in patient populations but also in healthy individuals has grown in recent years. Specifically in combination with cognitive training tES has shown success in enhancing cognition. However, to date, we still know little about the impact of interindividual differences on intervention outcomes. A variety of tES techniques and their effects in combination with cognitive training, interactive effects of tES with baseline cognitive abilities and neurophysiological traits will be presented and following ramifications with regards to the development of individualised stimulation protocols will be discussed.