Hi @Darling83,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
As the timber used to build fences is treated, we don't recommend much more than a good clean before painting. There are a few tips in this article on How To Spray Paint A Fence that are handy as a starting point.
The best thing you could do is give your fence a good clean with a pressure washer to remove any mould, algae, or built-up grime that can affect the adhesion of your paint.
If a pressure washer is not an option, a good scrub with a scrubbing brush such as this Oates Long Handle Deck Scrub Brush or this Sabco Bamboo All Purpose Heavy Duty Scrub alongside an exterior cleaner such as this Cabot's Exterior Cleaner, would be a suitable alternative.
Once the fence itself is clean, make sure to tidy up any weeds or grass at the base of the fence so you get good coverage from top to bottom of your palings.
There are premixed fence paints that you can use, but if the colour options do not suit, you can always use an exterior paint tinted to a colour of your choosing.
Let me know what you think and if you have any further questions, please don't hesitate to ask.
Jacob
