Helpful hints? You bet! When I teach, I try to get students to simplify what they are looking at into masses, or shapes of values. The easiest way to do this is to squint. Squinting is great, and it is the cheapest aid to learning to mass. Next to squinting, though, a reducing glass is wonderful! Thanks to another nice picture from Jim Comly (taken May 27, 2007 at the Southern Vermont Art Center demo), you can see that a reducing glass....well....reduces. It is just the opposite of a magnifying glass. By making things smaller, you do not see too many details, and seeing too many details, before seeing the general masses and underlying structure, is what holds beginners back. So, a reducing glass helps to simplify...very important! In addition to this, I use a reducing glass to view my painting, if I can't actually step back from my work. It gives the illusion of standing really far away.