I can't help either as I am fairly new at this and have not attempted anything that has a star. Would be interested in how they do it though.

It might help some if you spray starch/sizing each piece before you sew the pieces together. Then make sure each piece is cut accurately before sewing again.

Another hint is to pin the center point of the star when you put the 2 halves together, start in the center and pin to the outside edge, then sew from the center to one outside and then from center to the other outside edge. Do not overlap stitching at the center point, adds too much bulk.
Some times it helps to open the last seam and press it flat.

Remember to show us your block when you are satisfied with it.

I didn't see that any one mentioned this, but many folks will press seams open when you have several seams meeting at the same point as in your star...that spreads out the bulk. otherwise, the more you practice the easier it will be to make the points correctly.

Darn, I thought I was the only one who uses that trick. lol

I haven't made a star yet, but have chronic problems with "straightness". There was a tutorial on here that suggested using washable glue sticks to match and hold the edges of the two fabrics being pieced. So far, it works for me. But "so far" is only 2 blocks!

Others with more experience can weigh in on the glue stick method for stars.

I don't know if you were foundation piecing. I found that not pressing the points with 100 accuracy will cause them to be larger than they should be and they don't fit together right. I had to scrap a whole 12" star before I learned that lesson. Also, Carol Doak teaches to machine baste over the match points until they are right.