The following tutorial teaches you how to use the "live trace" feature in Illustrator.
If you want to change a hand drawn image to a Vector on illustrator quickly without drawing over your scanned image with the pen tool - you should use 'live trace'. It is useful when wanting to mock up concepts quickly but a more refined approach is usually needed for final outcomes.
1. Scan your hand drawn image to the computer
2. Open in Photoshop to adjust your hand drawn image so it has clear contrast between the black and white areas.
This can be done by opening your image in Photoshop then going to
Image ----> Adjustments -----> Brightness/Contrast
3. You will find that any grey lines may not get picked up in illustrator - so when you draw a design it is best to use a black pen or sharpie
Save your image as a PSD
4. Make a new blank artboard in illustrator
Then Place your PSD into illustrator
File > Place
5. 'Select' your image and click the drop down arrow next to 'Live Trace" then click on 'Tracing Options'
6. Tick the boxes next to 'Ignore White' and 'Preview'
Adjust the settings to get the best result you can click 'Trace'
7. Click 'Expand'
You now have a vectorised image!!!
To refine this image try clicking
Object > Path > Simplify
Then adjust the settings for the desired effect.
This is also how you can adjust the size of the image as it changes the amount of anchors in your design.