There are several things to consider when setting up an a compressed air system. First, if you do any painting, you cannot use an inline oiler. Doing so will coat your air lines with oil, which will contaminate your paint guns. Oil and paint do not mix well! It is not really that much off a problem to get in the habit of putting a couple of drops of oil in an air tool when you are done using it. I use a hypo with a square needle and run the tool for a couple of seconds to coat the insides with oil to eliminate internal corrosion during storage.
The other problem with compressed air systems is water. The amount of water that can be held in air without condensing out is relative to air pressure and air temperature. That is why you see humidity expressed as relative humidity. When air is compressed whatever water that is in the intake air is drawn in with the intake air. This air is compressed, but as it is compressed, it is also heated by molecular friction. If you are not using a great deal of air, it will cool in the tank and excess water will condense out. However, if you are using a lot of air the compressed air leaving the tank will still be hot enough to hold a great deal of water. This is where a drier comes in. The problem with mechanical driers is that they work by centrifical force against the walls off the container. Thus you have to correctly size your dryer to the air flow. In the case of dryers, bigger is not better! The only real way to dry your comressed air is to cool the air to the point where the relative humidity is too high too hold the water. Commercial Systems use mechanical cooling (air conditioners), but you can also cool the air by using radiators or by increasing the size of your delivery lines to give the air time to cool off. This system must also include gradiated lines, output loops, and sumps for draining the condensate.
Sorry for length of the message, but if you set up your compressed air system correctly, you will get good results with a minimum amount of daily maintenance.