i used to not grid my fabric but then i just started to do it now. i just stare at the original chart and start stitiching haha. i dont make a copy of the chart and mark off at all. ive messed up mayb like 3 times so far with the new one im doing. i used to mark a copy of the chart but then i notice that i started to mark off more than what i thought i did then in the end ruining the whole chart ;/ i use the blue water erasable fabric making pen though :) l0ve it so far!
I use a post it note, I place it under the line Im working on, with an arrow pointed to which square. If there is anything else I want to remember I write it on there as well. I used to have a magnetic board with a magnetic ruler to hold the pattern on....where the heck did I put that?
I also use marker to highlight my project to know where I am, and use a sticky note the know the recent area, as I sometime leave my projects for quite long hi hi, and also forgetful, but of course after make copy of the original pattern :)