1. Open a document with vectors to be scaled in Illustrator
2. Normally, items do not keep their proportions when scaled. To fix this, hold down the shift key while scaling an object! It will retain its original proportions
3. Normally, items when scaled end up in the area of the canvas where it was "stretched" to. To keep an item in one place while scaling it, simply hold the Alt key while scaling an object. It will be scaled in relation to its center point
4. These two tricks can be combined to scale objects that stay proportional and in correct relation to its center point