Convert background to transparent
Illustrator >> View >> Show transparency grid

Scale Tool
1. Click the “Selection” tool, or arrow, from the Tools panel and click to select the object you want to resize.

2. Choose the “Scale” tool from Tools panel.

3. Click anywhere on the stage and drag up to increase the height; drag across to increase the width. Hold the “Shift” key before you begin the drag to scale proportionately.

4. Double-click the “Scale” tool to resize the selected image using specific value percentages. Enter the values in the applicable fields. For instance, type “50” in the Scale field of the Uniform section to resize the image to 50 percent.