i went to a camerra shop and they sold a speicial lens paper that i use on my celeston nexstar 6 se all the time i mostly use cloth that you use to clean glasses with and sock it in water for 24 hours then sock it in the cleaning fluid for 6 hours you only have to do it when its new or about 6 months old and ive been doing that for about 18 months now and it dosnt scratch or hurt the optics.
my mum not knowing any thing about telescopes clead it with her hands and water and its still fine only the in side is breakable with my scope.
i find if you clean the stuff off every month so it dosnt stickit wont scratch the corecter plate.
good luck with what ever you use try not to do what i do i probly took 5 years off its life.
