Measure thrice, cut once.
Keep a sharp blade in your rotary cutter to accurate cutting.
There is no unwashed fabric in my quilting studio with the exception of one little stack and that is put away separately in a bag and labelled. That being said, I like my fabric to have "body" so I use Mary Ellen's best press liberally. Using this or starch helps keep bias edges from stretching out of shape.
All of this is my personal preferences. I'm a little bit anal (well, OK, a lot anal) and I like things to be precise. I have a friend who rarely has a perfectly matched seam or a perky point and she's happy as a lark with it. I'd be a lot less stressed if I were more like her - LOL.