Stars are reasonably easy, all you need is good protractor and compass.
1) Lay out your tape on a cutting surface. You'll need enough room to make marks for as large as is your protractor.
2) Use the compass to draw a circle for your star's diameter.
3) Set your protractror on the center of your circle, and mark every 72 degrees. Hopefully, as you go around, you'll find that your fifth mark is actually 72 degrees from the first mark.
4) Now draw lines from your 72 degree marks to the center of the circle. These intersections will be the points on your star.
5) Using these marked points and a straightedge, cut out your star.
As you can imagine, precision is important, particularly for smaller stars. If you have a magnifier, use it. You might find that making marks with a pin is more precise than with a pencil.
Use a good quality tape, my personal favorite being Tamiya Yellow tape, although 3-M's Blue painter's tape is pretty decent as well.
When cutting, use a sharp blade to cut the tape cleanly.