I have seen people who start practicing kendo in my dojo, that have experience, get very frustrated by initially trying to relate kendo to what they already know and by trying to apply what they know to kendo.
It is important to set aside (at least initially) any previous martial arts experience you might have so that you can come into the dojo with an open and receptive mind (Shoshin - beginner's mind).
This is because when you start your practice you won't really know enough about kendo to be able to reason well about it and map it into what you know (and vice versa). See Shu-Ha-Ri -- you need to start at Shu.