Find and reserve an affordable place to hold the conference. Keep in mind how many people you think will attend and how many rooms you will need to have for workshops. Decide on a theme or slogan for the conference. Decide if you will charge a registration fee. A large fee will discourage attendance, but if no fee is charged, some members may register but not show up.
Some conferences charge a fee just to cover the cost of meals.
Start publicizing the conference in union newsletters, at meetings and through stewards. Determine what workshop topics you want to offer and how many workshops you want to have. Select and invite workshop facilitators. Prepare a registration form and determine how you will get it out to members. You may want to include a list of workshops and ask people to pre-register.