I took a Lone Star class from Jackie Robinson. She told a story about making her first Lone Star and the big mountain in the middle. She actually taught classes expecting the mountain in the middle. She finally figured out a way to make Lone Stars without the mountain.
Her method is to make the strip sets and iron them. After that UNPLUG the iron and do not use it again until the squares and triangles surround the completed star.
To quote her pattern: "The bias is EXTREME, and any pressing or extra handling will change the shape, and give you a messed up corner."
She says to avoid any temptation to iron until all the strips are sewn together in the star and the background squares are sewn.
Also remember, DO NOT IRON! And when you do, PRESS. Set down the iron on the material, pick up move to the next spot, set iron down. PICK UP, do NOT slide iron!