They need standing water to reproduce, and it does not take much, anything that can hold water will be a breeding ground so try and eliminate that.
As far as keeping them away there is all kinds of stuff like candles, lanterns that burn citronella oil that help some, ThermaCell works pretty good.
The wife purchased a light for her gazebo that draws them in and traps them with a fan, it does work half way decent.. Then there is good old fashioned insect repellants.
Al