As others have said - figure out what you prefer, and work that way. I always press my seams, because I think the end result is better when I do. I also prewash everything (esp. since a disaster involved a blue & white quilt). Ironing that pile of fabric out of the washer is *not* my favourite activity, but it is an absolute necessity. After that, I only press before cutting if the fabric has a fold in it (ie, cutting when I folded the fabric to store it).

I press when machine piecing, usually with a dry iron. When I was a beginner I used a steam iron, but eventually realized that I am more accurate with a dry iron.

Having said that, I have read on the QB about people who have taken a class from Kaye England. If I understood those posts correctly, she does not press until the top is finished. I remember one post especially about a student who tried this out for himself and said he got better results with it. I haven't had the courage to try it myself.

As for starching, I do not prewash fabrics so there is enough stiffness in the fabric to give me accurate cuts. If I do have to prewash a fabric for some reason (if it does not pass my colorfast testing, for example) then I always starch the washed fabric before cutting to restore some crispness.

If I know I will be sewing long bias seams, then I heavily starch the fabric before cutting to keep the fabric stabilized while I work with it.

There are different ways to starch. I reserve spray starching for finished tops because overspray isn't such a problem for me then. If I need to starch yardage, I mix a solution of Sta-Flo liquid laundry starch and water, "paint" this on with a large wall painting brush, allow a couple of minutes for the starch to be absorbed, toss in the dryer, and then iron with steam. This is much less work than trying to spray starch yardage.

I always wash my fabric and am so happy I do. Each time I look at that dark red/blue/black/green/purple/yellow dye in my kitchen sink, I say "Thank you" to my quilt teacher. I do not iron any fabric until I am ready to cut it. Yes, I definitely iron my seams when piecing, something the same teacher taught me to do. My quilt blocks lay beautifully flat just like they should. Maybe there aren't Quilt Police out there but I think experience from bad results are my Quilt Police. I have never gotten into spraying my blocks with starch or anything, I know some women use 2 or 3 cans per quilt. I think that is your personal choice. I think if you are piecing a queen quilt top in one week, you must be doing something right.

I prefer to press and starch. Pressing after each seam helps me to keep things flat, and I am able to better match points, etc.
Perhaps try an idea for a while to see what works best for you~ :)

I too am a pre washer as I am allergic to the chemicals in the fabric making process. I will iron my yardage after I wash it. I used to be a a die hard Best Press kind of gal then I stumbled across the Bounce Pressing Spray. I love it! When I am ready to use a piece of fabric for a project, I will again iron and will do a light spray of either Best Press or Bounce Pressing Spray if it needs it. Might be a wasted step and a waste of product but I don't mind! When piecing, I press after every seam. I don't necessarily use anymore pressing product though. When my block is completed, I will give it a good pressing with a light spray of pressing product before I square it up.

(PS: I'm one of those weirdos that enjoys the ironing of my yardage after washing it. It is really cathartic for me, especially if I am in love with the fabric! Plus it gives me another opportunity to examine my fabric for any defects such as runs, snags, stains (even on brand new yardage!) or holes. I guess I spend a lot of time loving on my fabrics! I wonder if I should seek some kind of professional help. . . hmmm)

I agree that pre-washing and starching are personal choices. I personally don't do either...and I do press carefully every seam to help ensure precise matching...it really makes a difference in my experience.

I use Best Press before cutting, and at every step in the piecing process. I do not prewash unless the fabric is a color that might bleed, or if there is a strong dye odor.

Same above and do pre wash.

You should watch the first episode of Craftsy's Free BOM. She tells you how to straighten out your fabric you buy. Very interesting. Never knew that before. I always press with starch my fabric before I cut and press after I sew each piece. I love cutting and ironing. Just really enjoy that aspect of the sewing. I will use 'Faultless', 'Best Press', or 'Bounce' when ironing. I never over do it. But I love the crispness of it. If I am working with bias, I do overdo it quite a bit!! It's so relaxing to iron! But I encourage everyone to watch Craftsy's Free BOM first episode. The instructor is the writer of 'Quilts, Quilts, Quilts' from 1988 (?). She has some excellent ideas that I don't think any of us know about.

I always press and starch my fabrics before I cut. Even if you aren't going to starch them you do need to press them to get a good cut and in my opinion a better cut if starched.