Get a decent tour book and pick the best locations for yourself. I made the massive error of trying to fit in everything in a weekend. 15 years later I am stlil going to Ypres and the Somme and finding I havent even scratched the surface.
You havent said where you are going.
As stated a good tour guide book is the way ahead say Holts or Before Endeavours Fade by Rose Coombes MBE which covers both areas.