Work usually starts by identifying schemas, sometimes through conversation and sometimes with specialised questionnaires. Your therapist then helps you notice "modes": states such as the hurt child, the harsh inner critic or a protective part that switches feelings off.
Schema therapy combines cognitive, behavioural and experiential techniques. A well-known one is imagery rescripting, where you revisit a hard memory with your therapist and imagine it again, this time with the need that went unmet being met. Chair work and dialogue between different parts are also common.
The therapy relationship itself is a tool: within professional boundaries, the therapist offers warmth and consistency that may have been missing in the past.