Tutorial: Outlines handdrawn
Program: Corel PhotoPaint
Operating system: Windows
Inpudevice: Wacom Tablet
Often you got only a rough sketch or something more complex like a picture so your programm can't help you with outlines
How it works:
Because we want to use nice black lines afterwards we first have to care about the sketch lines. They need to get a bit color and bleeching so we can see the black color on them afterwards. My version to do so is shown in the Pics beneath.

Change the Picture to duotone. It can happen that instead of the yellow tone it remains grey... thats ok. Now we change it back to RGB to change the colors in a more 'black-friendly' way.

In view of the coming coloring step it's a good idea to make a higher resolution befor continuing. 300dpi and at leas 1700 px should be fine - depending of the size it should be when finished. After the coloring we change the resolution back to 100 or 72 dpi to get better results an to clear out some roughnesses.
Now put a new layer on the sketch and draw the mainlines. and add details if needed. I chose thiker lines and black shadows (Comic stile USA) To get a result more Manga/Anime like just make thinner lines and no shadow.