The good thing about fabric is that it stretches - you can nudge it a bit to make it fit. The bad thing about fabric is that it stretches - it makes it difficult to be consistent. We have to remember that we are working with a malleable medium which can shift and distort when cutting, sewing, and assembling. I have never been very successful cutting multiple layers of fabric so I don't do it. For others this is not a problem. Some can sew right along without pinning. I have to pin for things to come out right. The way you pin and the types of pins can make a difference. I have the agree the thinner the pins the more accurate my matching is. Some people can sew fast and chain piece. I find that I have to go slower and be careful about chain piecing because I lose track of which piece goes to what. Some people can finger press and move on. I find that I have better luck pressing with an iron before I move on. Some people pull their fabric through when sewing. I find I have better luck by letting the machine pull the fabric through as it stitches and only using my hands to gently guide the fabric through. The point is what works for some doesn't work for others. I think practice makes a difference and finding your own rhythm will come. Use the tips of others but don't become so OCD over it that you lose the enjoyment.