Some people here have hit on important steps in getting good air. But first relates to compressor sizing. You need a bigger compressor CFM wise than your biggest use, double is a good starting point. Reason: reciprocating compressors are not designed to operate continuously. The high temperatures they reach that way will cause degrade of the oil and result in deposits that shorten the life of the compressor. Don't judge a compressor by it's HP or tank size! CFM should be stated at 90 psi, industry standard. There are a lot of "cheater" 5 hp compressors sold. It's air output you are interested in, not "hp".
Since air is heated when compressed, it can hold more water vapor. As that air cools the water vapor condenses and puts that water into your tools. Water damages almost every kind of tool and is especially bad when spraying finish. So after the compressor you need to cool the air and then separate the water. Air to air coolers are a good first step. You can buy one or make a reasonable one from fin-tube elements made for heating with a boiler, & a fan. Provide a slope and a drain at the bottom. Next is some way to remove the remaining water vapor. You can make a desiccant drier out of a piece of pipe, some SS steel screen and a few fittings, or buy a commercially made one. You can buy bulk desiccant on Amazon that changes color to indicate when it needs changing. Don't throw it away, spread it on a cookie sheet in you wife's oven and heat it slowly. You can tell when it is done by the change in color.
An alternative to the desiccant drier is a refrigerated drier. They tend to be expensive but are the industry standard. The next item you need for clean air is a coalescing filter to remove any oil or other contaminates. It is just a tube with a filter that catches the oil mist that has been condensed from the oil vapor put out by the compressor. It will have a bottom drain and a gage that shows when it is time to change filters. The last item is your pressure regulator. If you have expensive equipment, put a small desiccant drier right at the equipment also. Run you piping so there is a continuous slope to a drain(s.)
Compressed air is expensive to generate, seal up all leaks and don't let air bleed from the drain on the compressor. My shop has all of the above items serving a 25hp screw compressor and a 10hp backup. Kaiser has a good online presentation on air systems.