How to activate developer mode in Odoo
Multiple versions covered
Activate Developer Mode in Odoo 9 or older
Click on the user in the right corner, then "About" and "Activate Developer Mode".
If you can't do this you should activate "Technical Settings" in the Settings/Users.
Odoo 10 & Odoo 11
Since Odoo 10 the Developer Mode is activated from Settings.
Activation link is located just below the "Share the Love" box.