This tutorial will tell you simple ways to smooth out the lines in Illustrator. It can save you a lot of time.
1. Pencil and Paintbrush Tool Settings
To open the Pencil tool preference pane, double click on the Pencil tool. Set the amount of smoothness you like to get. Drag both sliders to the maximum setting. The smoothness option is pretty straight-forward, but the higher the fidelity, the fewer anchor points Illustrator will create.
Click OK. The Paintbrush Tool has the same options which you can use instead of the Pencil.
2. The Smooth Tool
Click and Hold on the Pencil tool and select the Smooth tool. Just double click on the Smooth tool to open the Smooth tool preference pane. Just like the Pencil and Paintbrush, the Smooth tool has fidelity and smoothing options.
Change these settings based on your preference to get the right amount of smoothing. Draw or scribble a rough path with the pencil (or Paintbrush). Select the path and using the Smooth tool, click and drag across your selected path to smooth it out.
Repeat until get an acceptable result:
Notice that the Smooth tool also reduces the amount of anchor points in your path.