Conversion: manga to Chibi

When you're drawing a cartoon figure, you take what makes that thing, e. g. a cat, and take the features that make that cat a cat (triangle nose, triangle ears, whiskers) and put them together to create a cat. ( I suggest watching Will Terry's drawing for kids 2 starting at 1:40, he displays this concept well)

Looking at this chibi and the picture on the right, you can tell which character he's supposed to be; why? Because they shares core similarities. 
When you're drawing a chibi OF a character, you have to make sure that they have core similarities between manga and chibi, so that your chibi isn't just another blond boy in a t shirt.

Several (!) similarities
1. Rect. glasses
2. Hairstyle. Don't copy every spike- just the prominent ones
3. eyes and eyebrows- take care to mirror the face of your manga character
4. Jacket+props
When drawing a chibi be sure NOT to copy every wrinkle- remember, it's a chibi!