Or if your visualization skills are not yet up to par you could just cheat and use several boards. I use a regular size board and pieces for the main line and then I have a 12" magnetic folder (glued, doweled, and duct taped permanently open) for the variations. And yes I have been known to use a 7" magnetic folder (similarly duct taped open) for variations within variations. I'm working on visualization but right now it's what I have to do if I want to follow games without getting lost and frustrated.
Going through variations when playing through master games
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I recently acquired a whole bunch of chess books/games collections---- do you guys recommend going over all the lengthy 10 move side variations of those GM games? Usually I tend to skip them and only do them if its like 5 moves or less (that way i can sort of envision the resulting position without having to move the pieces)