Forgiveness in a bow is really just another way of describing it's resistance to torque. Heavier resists torque better than light. Longer better than shorter and higher brace heights better than lower. Many other factors affect forgiveness, but they are not directly related to the design of the bow. They include things like how well the arrows are matched to the bow, how well the bow is tuned and the timing on the cams, among others.

Like Arthur said, a repeatable grip is very important. This is an area that I believe is almost ignored by most manufacturers. They make grips that are comfortable, not ones that are designed to make hand placement easily repeatable. In general, the grips feel good and suck at the job they are supposed to do. I think this may be due to all the advise I see on choosing a bow with a "grip that feels good". Poor advise in my opinion. The grip should be easily repeatable. "Feeling good", has little to do with proper archery form.

Another area that affects forgiveness is the draw weight of the bow. If you are close to your maximum draw weight, then the other factors will become more critical. Likewise, if your drawlength is wrong, then torque will be applied differently and with less consistancy.

All this stuff is more important to beginners than it is to professionals. Target archers tend to be more concerned about it than hunters shooting at close ranges. Although a hunter is likely to be concerned with brace height because high ones are more forgiving in regards to the string hitting their hunting jacket's sleeve. It's hard to hit a deer if the string hits your sleeve.

Sometimes it's difficult to determine if a bow is unforgiving because of it's design, your setup, the lack of good tuning or a combination of them all. When you find one that does qulify as "forgiving", hold on to it. Upgrading to the "latest and greatest", seldom brings the results we hope for.