The Dream Orbs you collect in the game can be used to purchase several different upgrades in the Development Lab. A good strategy is to only focus on improving your Scope as this will greatly increase the dream clouds that appear during a single-play session and so increase the rate at which you collect more orbs and Pokemon.
Normally you play Pokemon Dream Radar by standing up and holding your 3DS in front of you turning your whole body left and right to search for clouds to shoot. You can make this a lot easier by playing on a swivel chair where you can just spin around while sitting. Doing this will extend your playing time as you won't get tired so quickly and your arms and neck won't get sore.