Even if you have not done anything for your wood fence maintenance, it is never too late to begin and this is a good habit to develop. One day you may decide that you want to move, and then this is when your efforts will pay off. So that that will get your attention and inspire you to take regular action, but most importantly, maybe give your fence a good visual inspection. You would naturally want to know about issues and the various things that can attack your fence.
If you have not yet made your fence purchase, then one consideration could have been to learn what is needed for maintenance with the various kinds of wooden gaps on the market. But a picket fence can look so much nicer than others made from the same material, and this may introduce an offsetting feature that compensates for extra maintenance activities. The usual delivery time with parts can vary, and this is where going with an in-country fence maker will be easier to deal with. There is not much to a picket, and in this instance doing it your self can be done and with little assistance. Any time you call a contractor with a broken part of your fence, he will want to order a new part and charge you extra for it. In general, there is not a lot to the inner machinations of wood wings, but you want to avoid corrosion issues. You do have some matters of recourse and prevention though and they're not hard to implement. In time, dirt and dust will become mixed with the oil you have applied, and this can actually have a reverse effect than what you intended. Never let a rust situation go because it is really damage to the metal, and you have to attack it with proactive response.
Be very careful about mold, and this will also depend on where you live because some climates see it more than others. Stains are not highly durable to some chemicals, and a good example of this is using water and bleach for cleaning purposes. So you can easily use your garden hose and make sure you have some decent water pressure which brings us to power washers which are really good for cleaning wood wings. A regular hand regulator could work all right, and in the beginning you just have to test and experiment.
The exact nature of your wood fence care and maintenance plan will depend to a good extent on what you have. And you have to take everything into consideration as far as what is needed. So be sure you adhere to any directions you receive for the proper care of your fence.