Most folks want clean line art, and if this is what you’re seeking, scan at least at 600 DPI, though 1200 DPI is even better. Open your scan in Photoshop to convert your file to the Image mode of Bitmap via the 50% threshold method and an output of 600 – 1200. If you lose too much detail, you can make adjustments to your image by using Image Adjustments > Levels or Image Adjustments > Brightnesss / Contrast.
If you’d like a halftone, you can use a 300 DPI scan. With halftones, keep the image in the grayscale color mode in Photoshop, and let us know the LPI / line screen.
Either way, save your image as a TIFF with LZW compression. This will make your file size more manageable when placing into another program like Illustrator or uploading to your job ticket.