it's really not that complicated, you just have to understand why condensation is happening in the first place. it's always because the glass is colder than the moist air it is touching. there are two strategies to deal with this: either blow air with very low relative humidity over the glass, or fix the temperature differential itself. if you're using the "blow dry air" strategy, you always want to turn on AC and at least some heat, as this will create low relative humidity.

now in the winter you can sometimes do better than this by fixing the temperature differential itself. you can either lower the windows or cool the entire interior by blowing air with no heat. in reality, most people don't actually want to drive around in the winter with windows down or no heat, so the best tolerable option is usually to do as above: turn on AC and heat.

in the summer you can also get fogging on the outside of the windows. just use your wipers for this.