If you've made a rail fence baby quilt, it's probably not a good idea to jump right into a king-sized lone star. Odds are, it will end up in a box - half done in odd angles. (Yes, I have one of those)
Yes, it is not much fun to do a lot of the prep work (washing, pressing, cutting, etc) BUT doing those steps as precisely as you can WILL save you hours of frustration later.
Paying attention to pressing the seams is a big deal. Nesting seams make the quilt lay better.
There is not ONE WAY to do everything. Almost every step in quilting can be accomplished in many different ways. Find what works for you. You may change your mind from quilt to quilt. For example, I mostly press my seams to the dark, but at times I press to the light or I press open - it all depends on the project.