When you go to print your design click the Properties button in the Print window. In the Properties window click on the Graphics tab at the top. In the Graphics section under Halftoning click on the radio button marked "Use settings below". This will allow you to change the dpi and the screen angle. Those settings will be based on what mesh count the screens are that you are using. Below are some examples that produce good results.
123 mesh:
35dpi/30, 37, or 45 degrees
45dpi/33 degrees
156 mesh:
35dpi/37, 33, or 35 degrees
45dpi/33 degrees
180 mesh:
45dpi/30 or 37 degrees
35dpi/33 or 37 degrees
230 mesh:
35dpi/30,33,37, or 45 degrees
45dpi/ 33 or 45 degrees
65dpi/30 degrees
355 mesh:
35dpi/30,33,37, or 45 degrees
45dpi/33 or 45 degrees
65dpi/30 degrees
Results will probably vary based on your equipment. Definately experiment first before using this on a real job.
Good Luck!