There is no magical formula; it all depends of your imagination. However, it is advisable to install the light projector at a distance of 25 to 35 feet and you might consider getting a second one if you want a special effect.
Depending of your particular setting, such as existing street lights, the actual size of the house and the way you want the final set-up to look like, you could try putting one of them further away for a diluted effect. Experiment with the lights until you get the dream lighting you aim for and eventually share your masterpiece.
For more info check out our Ultimate Guide to Laser Xmas Lights – http://laserchristmaslightshq.com/ultimate-guide-christmas-laser-lights/
Or our Holiday Projector Guide explaining the five highest quality and most affordable projectors on the market – http://laserchristmaslightshq.com/best-laser-light-projectors/