Sue, when I sew it's usually with lots of interruptions, so I may do things you won't have to.
I like to chain piece my pieces since I have to make a small trek from the sewing room to the ironing board. There just isn't enough room in here for it.
If I have a block that is a bit complicated, I put the stack of pieces in the actual shape of the block. Then I don't accidentally sew the wrong pieces together. I don't like the task of pinning, but I have found that even one along the seam that is supposed to be sewn is very handy. I run all of the same pieces through one after another, then cut them apart, iron them, and bring them back to the puzzle, I mean block pattern. It may seem like it takes longer to make progress this way, but I have all of the blocks done at about the same time.
I will use the dining table, living room floor, or my own bed as a layout surface. I have been known to pin a small tag with the row and column position on each block after I have finally determined the best layout. Like A6 or something that makes sense to you. Then I can stack the blocks near the machine and clear the layout surfaces for their original purpose, and not mix up the blocks. Sometimes I have a little helper that likes to look at things, and doesn't always put things back the way they are supposed to be when she is done. So that step is incredibly helpful to my sanity.
The best way to get better at anything is practice! I am sure your sister will love the quilt when you are finished. It sounds like you already have happy memories of getting it started.
Good luck with it!
Cathy