The first step to preparing your roof for the wet season is to clean the gutters. Remove all of the leaf litter from the gutters and check that the downpipes aren't blocked.
Safety is important when you're working on a roof. If you're standing on the roof to clean it, always start on one side and walk backwards away from where you have sprayed. That way you always walk onto a dry part of the roof. If you're working from a ladder, have someone on the ground holding it for you.
Before you start this step, disconnect any water tanks from the gutters so chemicals don't run in to your water storage. Put on safety glasses, dust mask and rubber gloves. Following the instructions on the roof cleaner, spray it onto the roof. Scrub the roof with a brush. Hose the roof cleaner off with water.
If you have a tin roof, check that all of the screws are securely fixed. Replace any that are damaged. If any of the seals around the screws are worn, use silicone to reseal them.