Here are three online guides to portrait drawing. These should help you learn about proper placement of all of the facial features and will give you some tips about how to make your self portrait more realistic.
The first link gives a basic overview of drawing a proportional face. The second link is more detailed and focused on making your portrait as realistic as possible. The third link will help you break down the face into each individual feature.
Choose the one that is right for you, use what you can from the online lesson and proceed at your own pace!
Click here to watch a "Show Me" tutorial about portrait drawing:
Check out this link for a more detailed tutorial about drawing realistic faces: