The trick I've found to getting the streaks is just keep going over it with new cotton; first damp then dry but only use cotton once and throw it away. I use the 100% cotton pads you get from the cosmetic area at Walmart or wherever.

Also, I don't use the mixture Celestron suggests, I only use about 10% alcohol and 90% distilled water. (They don't even recommend distilled water...?)

I don't think you'll notice the streaks visually but I don't know about imaging.