Here are a few tips on how to solve this if you have not read the book
1. If the grave digger gets confused between Hamlet Sr and Jr go to another character
2. Rose and Guild need to be asked at the same time or else the GD will be confused
3.Some times questions will need to be repeated before a grave gets an X
4.Claudius needs to be solved in order to figure out Hamlet Sr's death
5.Some questions need to be solved by trying to finish the grave for example:
GD:"It couldn't happen unless..."
Player:"Unless (person#1) was mistaken for (Person#2)" Then you'll get an X
6.For Ophelia's reason ask "How did Ophelia become mad?" to GD
7. Others will sometimes need to be solved to help find out a single character
8. Some questions will have to be answered straight forward
If all else fails look on google I hope this helps and have fun