The following resources are specifically for counsellors and psychotherapists working with trans people, please let let me know if I have missed any good resources!
Check out the general resource list as well to expand your understanding
Conversations with a Gender Therapist: 5 Things You Can Do to Promote Transgender Awareness
Ari Lev – Transgender Emergence: Therapeutic Guidelines for Working With Gender-Variant People and Their Families:
DSM V Gender Dysphoria Fact Sheet
Trans* and Feminist Friendly Gender Resources 