I used to draw on my map along the leg where I wanted to do FREDA checks, change frequencies, cut offs for any clearances (e.g. entering a MATZ) and so on.
I found this much easier than constantly having to refer to both map and plog to find where I was, and when i next needed to change tanks or frequencies.
The absolute key to flying VFR dead reackoning is a Very Good Look Out. If you look out both to the sides and far ahead, you will see any nav features in advance and won't find yourself constantly looking at the map trying to pin point your posistion.