Things that I've found that will increase set:
1. Wet wood. Moisture content >12%.
2. Poor design
3. Uneven tiller
4. Poor tiller (rushing tiller, pulling beyond desired final draw weight, not all of the limbs working evenly)
5. Unkind treatment (leaving a finished bow braced for long periods when not in use, leaving your bow in direct sunlight or a hot vehicle)
1" of string follow is nothing!! If that's all you have, you've done very well. Anything up to 2" is fine. Actually, a bit of string follow is a good thing. It makes the bow sweeter to shoot, more forgiving, less hand shock, and like Hillbilly mentioned, probably more accurate.