For small prints, where high resolution is not so critical, or if you just want a few copies and need to keep costs down, you can create a print from your own digital file using your desktop scanner. Scan your image at as high a resolution as possible - for best results you'll want 300 dpi output, 350 or higher for fine detail. Resampling a lower resolution file doesn't give good results - you need a high resolution scan to ensure all the detail in your drawing is captured.
Digital photographs can be particularly problematic, rarely giving enough detail for successful printing, though some of the more sophisticated models - 5 megapixels and above, with high quality optics - may produce acceptable results. If you are confident in your photographic skills, with access to good quality studio equipment, you can certainly take your own photographs, but otherwise, its best left to the experts. Remember - the final image can only be as good as the source data that the printer has to work with.