I also trace the nose, mouth, and eyebrows, with the pencil tool to make sure I get the shape just right.

If you don't like the way something turned out when you traced it, you don't have to delete and start over on that shape, you can edit it using the Direct Selection Tool (the white arrow in the top right of the toolbar, or press 'a' on the keyboard)

Drag a selecting over the shape you want to edit and it's edit points will appear. Drag a selection around the point or points you want to edit, and the control lines appear. These lined-points are called the directional points and determine the length that the angle of the directional point to the anchor point affects the line you are drawing.

If you draw a line freehand and go to edit it and find that there are way too many points in it, and editing results in some weird twists or bends in the curve, then you can remove some of the points to simplify it. Click and hold down on the Pen Tool from the tool Bar and choose the Delete Anchor Point tool. Simply click on the anchors you don't want and they'll disappear.

You'll probably need to edit the anchors and directional points of the remaining points, but it will be easier to adjust the lines if there are fewer anchors to deal with. These rules go for all lines in illustrator, not just the lines with the pencil tool.

Once you have these areas done, hit the swap colors arrow by the fill and stroke swatches, but make sure that none of your shapes are still selected when you do this, or it will swap the settings on that shape!

Choose the Paintbrush Tool from the toolbar (the 'b' key on the keyboard is a shortcut key). Select one of the smaller brush sizes from the Brushes window, and trace the lines around the eyes that weren't done before using the pencil tool.

To see what your lines look like, without the pencil sketch in the background, click on the eye icon next to the Layer with the pencil sketch on it. This will make it invisible. You can click the eye icon again to make it visible again.

For a lot of lines, I simply use the paintbrush tool and draw freehand, but some lines need to be very smooth, or are too long to keep the line constant while drawing freehand. For these lines, I use the pen tool.

I almost always use the pen tool when lining long, curved, areas of hair. On shorter areas, or parts that have a lot of smaller curves, I use the paintbrush for better control.

Choose the Pen Tool from the toolbar. Click at the end of one of the lines you want to trace, but don't release. Drag outwards a bit to create the Directional Point (the line that determines the amount of the curve that is affected by the angle of the curve). Click your second point and drag the directional point out until the curve fits the line of the pencil underneath. If the line you wish to create continues and has more curves, continue creating more points until you are finished with the line. Once finished press the P key to end the line and start a new one.

By default, the pen tool does not use any of the brushes, but you can tell the line to be stroked with one of the brushes anyways. While the line is still selected, simply click on the Taper Stroke Brushe of your choice from the Brushes Window and the line becomes stroked with that brush.

Using the Pen Tool takes practice, and in the beginning you will be editing a lot of your lines to fit the pencil drawing better, but as you practice more, less and less editing will be necessary.

Finalizing

Okay - just keep going. Make sure you vary the thickness of your lines where it seems nessecary (and remember you can change the thickness whenever you want simply by selecting the line and clicking on a different brush). It's also good to often turn off the pencils layer to make sure that all your lines are meeting at the tips.

When you're done, make sure that you save it with the pencil's layer turned off. (click on the eye next to the layer to make it invisible. This is really important! So don't forget!.

When you're sure you're completly finished, close illustrator and open photoshop. (if you don't have photoshop then you'll have to export the .ai file in illustrator. Before closing illustrator got to File > Export: and pick a format that you know your graphics program can open. If you're using Paint Shop Pro, use the .psd file format because it will keep the lineart on it's own layer with invisiblities.)

In Photoshop, choose File > Open and find the .ai file you saved with illustrator. Open it.

The above window will appear. Make sure all the settings are the same as shown in the image. (width: 100 , percent; height: 100, percent; resolution: 300; mode: RGB; antialias: on)

The Lineart should be on it's own layer, and there won't be a background layer. You'll probably need to make a new layer below your lineart and fill it with white for a background while you work on your image.